Opt out in closed event (4,3)
I believe the answer is:
shot put
'event' is the definition.
(shot put is a kind of event)
'opt out in closed' is the wordplay.
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'in' is an insertion indicator.
'closed' becomes 'shut' ('shut' is associated in meaning with 'closed').
'opt' anagrammed gives 'otp'.
'otp' going into 'shut' is 'SHOT-PUT'.
(Other definitions for shot put that I've seen before include "Athletic field event" , "Throwing contest" , "Olympic event" , "Throwing event" , "Competition in which a heavy metal ball is hurled" .)