Not knowing the complete situation, I can't be certain how to instruct you, but use the Bible to help you do what is right. There are two ways to approach this from scripture that I see.
First off Gossip and slander is a sin, and an elder of a Church should know this. If he is just talking to everybody about this and it bothers you, maybe you should ask him what he has against this person so much that he would not go to the person face to face, as a brother, and make things right - as the Bible also says to do this. If he doesn't have something against this fellow he speaks against and behind the back about, tell him it is wrong to slander another person behind their backs in humble prayerful manner. If he doesn't want to hear it and starts more trouble, then go to the pastor or another elder for help and advice.
Read God's Word, pray over it and about the situation, and then do as you think the Holy Spirit tells you from the truth of scripture.
Matthew 18:15 Moreover if thy brother shall trespass against thee, go and tell him his fault between thee and him alone: if he shall hear thee, thou hast gained thy brother.
16 But if he will not hear thee, then take with thee one or two more, that in the mouth of two or three witnesses every word may be established.
17 And if he shall neglect to hear them, tell it unto the church: but if he neglect to hear the church, let him be unto thee as an heathen man and a publican.
Matthew 5:23 Therefore if thou bring thy gift to the altar, and there rememberest that thy brother hath ought against thee;
24 Leave there thy gift before the altar, and go thy way; first be reconciled to thy brother, and then come and offer thy gift.
2 Thessalonians 3:11 For we hear that there are some which walk among you disorderly, working not at all, but are busybodies.
1 Timothy 5:13 And withal they learn to be idle, wandering about from house to house; and not only idle, but tattlers also and busybodies, speaking things which they ought not.
1 Peter 4:15 But let none of you suffer as a murderer, or as a thief, or as an evildoer, or as a busybody in other mens matters.
Psalms 41:7 All that hate me whisper together against me: against me do they devise my hurt.
Proverbs 16:28 A froward man soweth strife: and a whisperer separateth chief friends.
Proverbs 26:22 The words of a talebearer are as wounds, and they go down into the innermost parts of the belly.
Romans 1:29 Being filled with all unrighteousness, fornication, wickedness, covetousness, maliciousness; full of envy, murder, debate, deceit, malignity; whisperers,
2 Corinthians 12:20 For I fear, lest, when I come, I shall not find you such as I would, and that I shall be found unto you such as ye would not: lest there be debates, envyings, wraths, strifes, backbitings, whisperings, swellings, tumults:
Psalms 31:13 For I have heard the slander of many: fear was on every side: while they took counsel together against me, they devised to take away my life.
Psalms 101:5 Whoso privily slandereth his neighbour, him will I cut off: him that hath an high look and a proud heart will not I suffer.
Proverbs 10:18 He that hideth hatred with lying lips, and he that uttereth a slander, is a fool.
Proverbs 11:9 An hypocrite with his mouth destroyeth his neighbour: but through knowledge shall the just be delivered.
Jeremiah 9:4 Take ye heed every one of his neighbour, and trust ye not in any brother: for every brother will utterly supplant, and every neighbour will walk with slanders.