Aggressively masculine revolutionary embraces church (5)
I believe the answer is:
macho
'aggressively masculine' is the definition.
(macho means aggressively masculine)
'revolutionary embraces church' is the wordplay.
'revolutionary' becomes 'mao' (Chinese leader Mao Zedong).
'embraces' is an insertion indicator.
'church' becomes 'ch' (common abbreviation).
'mao' placed around 'ch' is 'MACHO'.
(Other definitions for macho that I've seen before include "Butch" , "Jock" , "Laddish" , "Ultra-masculine" , "Ostentatiously virile" .)