Fail for lack of practice, primarily (4)
I believe the answer is:
flop
'fail' is the definition.
(flopping is a kind of failing)
'for lack of practice primarily' is the wordplay.
'primarily' suggests taking the first letters.
The initial letters of 'for lack of practice' is 'FLOP'.
(Other definitions for flop that I've seen before include "turkey" , "Fail" , "Fall clumsily, liked failed play" , "Fall limply - box-office failure" , "Collapse loosely - total failure" .)