Devoted, a group getting behind party (7)
I believe the answer is:
adoring
'devoted' is the definition.
(I've seen this before)
'a group getting behind party' is the wordplay.
'group' becomes 'ring'.
'getting behind' means one lot of letters go next to another (some letters go behind others).
'party' becomes 'do' (do is a kind of party).
'ring' put after 'do' is 'doring'.
'a'+'doring'='ADORING'
(Other definitions for adoring that I've seen before include "Showing great affection" , "Worshipful" , "Loving, worshipping" , "Holding dear" , "Being very fond of" .)