Model keeping uniform for clubs, maybe (4)
I believe the answer is:
suit
'for clubs maybe' is the definition.
(clubs is a playing card suit)
'model keeping uniform' is the wordplay.
'model' becomes 'sit' (e.g. for a painting).
'keeping' indicates putting letters inside (some letters kept inside).
'uniform' becomes 'U' (phonetic alphabet: alpha, bravo, charlie etc.).
'sit' enclosing 'u' is 'SUIT'.
(Other definitions for suit that I've seen before include "Formal wear for men" , "Jacket and trouser set" , "Go well with; clothing" , "fit" , "Part of pack (of cards)" .)