Grab form of crow (4)
I believe the answer is:
brag
'crow' is the definition.
(I know that crow is a more specific form of the action brag)
'grab form' is the wordplay.
'form' is an anagram indicator (another form of the letters).
'grab' anagrammed gives 'BRAG'.
'of' acts as a link.
(Other definitions for brag that I've seen before include "Idle talk" , "Show off, crow" , "Boast about garb" , "popular with 15 [EGOTIST] , no doubt" , "Boast ? card-game" .)