Escort partners inside gathering (7)
I believe the answer is:
brewing
'gathering' is the definition.
(thesaurus)
'escort partners inside' is the wordplay.
'escort' becomes 'bring' (I've seen this before).
'partners' becomes 'ew' (East and West are partners in the game bridge).
'inside' is an insertion indicator.
'bring' enclosing 'ew' is 'BREWING'.
(Other definitions for brewing that I've seen before include "Making tea" , "Making beer" , "drink in one go" .)