Enthusiastic clique supporting Gunners (6)
I believe the answer is:
raring
'enthusiastic' is the definition.
(as in 'raring to go')
'clique supporting gunners' is the wordplay.
'clique' becomes 'ring' (I've seen this in other clues).
'supporting' is a charade indicator (letters next to each other) (in a down clue, some letters go below others).
'gunners' becomes 'RA' (Royal Artillery).
'ring' after 'ra' is 'RARING'.
(Other definitions for raring that I've seen before include "Agog" , "Eager (to go?)" , "Very keen (to go?)" , "Eager, impatient" , "Very eager (to do something)" .)