'Uncle Sam' I suspect is macho (9)
I believe the answer is:
masculine
'macho' is the definition.
('masculine' can be similar in meaning to 'macho')
'uncle sam i suspect' is the wordplay.
'suspect' indicates anagramming the letters.
'uncle'+'sam'+'i'='unclesami'
'unclesami' with letters rearranged gives 'MASCULINE'.
'is' acts as a link.
(Other definitions for masculine that I've seen before include "Calumnies about male equality" , "Butch" , ""Man" is clue (anag)" , "Calumnies about macho type" , "Possessing qualities of a man" .)