Does divorce disqualify a man from being an elder? Is adultery covenant-breaking?
Adultery does break the covenant or "law" between a man and woman. "Or do you not know, brethren (for I speak to those who know the law), that the law has dominion over a man as long as he lives? For the woman who has a husband is bound by the law to her husband as long as he lives. But if the husband dies, she is released from the law of her husband. So then if, while her husband lives, she marries another man, she will be called an adulteress; but if her husband dies, she is free from that law, so that she is no adulteress, though she has married another man" (Romans 7:1-3).
Since an elder is required to be the husband of one wife (I Timothy 3:2; Titus 1:6) and the Greek is clear that he must currently be the husband of one wife, then a man who used to be the husband of one wife no longer qualifies for the position.
Now, it is possible that you are asking if a man who was remarried after a divorce still qualifies to be an elder and the answer there depends on the reason for the divorce. Jesus allowed a person to divorce his spouse because of sexual immorality (fornication) and could marry another (Matthew 19:9). Since Jesus allowed it, we cannot use that situation to disqualify a man from being an elder. However, if the divorce was because he had committed adultery or was for some other reason and he has married again, then he is in adultery and he should be withdrawn from until he leaves his sin. Consideration for eldership doesn't even enter the picture in such a case. "But I say to you that whoever divorces his wife for any reason except sexual immorality causes her to commit adultery; and whoever marries a woman who is divorced commits adultery" (Matthew 5:32).