508 (roughly) reject play on words? Relax! (7,2)
I believe the answer is:
lighten up
'relax' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for lighten up that I've seen before include "Unwind" , "Chill" , "Relax!" , "Plug in the fire" .)