Great blokes in semi-rough (7)
I believe the answer is:
immense
'great' is the definition.
(immense can mean great or huge)
'blokes in semi-rough' is the wordplay.
'blokes' becomes 'men' (bloke can informally mean a man).
'in' is an insertion indicator.
'rough' indicates an anagram (a rough or broken ordering of the letters).
'semi' anagrammed gives 'imse'.
'men' placed inside 'imse' is 'IMMENSE'.
(Other definitions for immense that I've seen before include "Unusually great in size" , "Superb" , "Huge, considerable" , "Unusually large or great" , "Huge, really great" .)