godan verb (-u), transitive verb
explain away; make excuses for; gloss over; talk one's way out of
Used when someone tries to cover up a mistake, failure, or awkward situation with words, often in a somewhat evasive or smoothing-over manner.
彼は遅刻の理由を言い繕おうとした。
He tried to explain away his lateness.
Instead of making excuses for your mistake, it's better to apologize honestly.