Enthusiastic male group heading off (6)
I believe the answer is:
hearty
'enthusiastic' is the definition.
(I've seen this before)
'male group heading off' is the wordplay.
'male' becomes 'he'.
'group' becomes 'party' (party is a kind of group).
'heading off' means to remove the first letter.
'party' with its initial letter taken off is 'arty'.
'he'+'arty'='HEARTY'
(Other definitions for hearty that I've seen before include "Loudly vigorous and cheerful" , "sporty type" , "Vocally cordial in earthy way" , "Strong, healthy" , "Robust - sailor" .)