Frame in competition — lose it (5,2)
I believe the answer is:
crack up
'lose it' is the definition.
(both can mean to go mad)
'frame in competition' is the wordplay.
'frame' becomes 'rack' (rack is a kind of frame).
'in' is an insertion indicator.
'competition' becomes 'cup' (eg the FA Cup).
'rack' inserted into 'cup' is 'CRACK-UP'.
(Other definitions for crack up that I've seen before include "Burst into laughter" , "Suffer breakdown" , "Have a nervous breakdown" , "Laugh without restraint" , "Collapse under strain; praise" .)