'Stop obsessing!' (3,2,2)
I believe the answer is:
let it go
'stop obsessing' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for let it go that I've seen before include "Hit song from Disney's 2013 animated feature film Frozen" , "Refrain from comment" , "Excuse something" , "Disney tune" .)