Brag about snatch (4)
I believe the answer is:
grab
'snatch' is the definition.
(synonyms)
'brag about' is the wordplay.
'about' is an anagram indicator.
'brag' is an anagram of 'GRAB'.
(Other definitions for grab that I've seen before include "Seize hold of" , "Take quickly" , "Grasp roughly" , "Seize roughly" , "'Seize, snatch (4)'" .)