However, chap's half masculine (5)
I believe the answer is:
butch
'masculine' is the definition.
('butch' can be similar in meaning to 'masculine')
'however chap's half' is the wordplay.
'however' becomes 'but' (I've seen this before).
'half' means to take half the letters.
'chap' cut in half is 'ch'.
'but'+'ch'='BUTCH'
(Other definitions for butch that I've seen before include "Markedly masculine" , "Macho" , "Aggressively masculine" , "Acting as a male (colloq.)" , "Tough" .)