To Restrain, To Refrain
If 遠慮 is "decline" or "restrain" then the verb vocab version is to decline or to restrain.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own. Also, the reading comes from 遠慮.
Tomorrow is my physical check-up, so I’d rather not have alcohol today, if that’s okay.