Carefree British drunk male (6)
I believe the answer is:
blithe
'carefree' is the definition.
(synonyms)
'british drunk male' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'drunk' becomes 'lit' (I've seen this in another clue).
'male' becomes 'he' (he refers to a man).
'b'+'lit'+'he'='BLITHE'
(Other definitions for blithe that I've seen before include "Heedless" , "light" , "Carefree and happy" , "'' ... Spirit'', Noel Coward play" , "Merry" .)