Stomach sailor and crew holding party (7)
I believe the answer is:
abdomen
'stomach' is the definition.
('abdomen' can be a synonym of 'stomach')
'sailor and crew holding party' is the wordplay.
'sailor' becomes 'ab' (abbreviation for able seaman).
'and' is a charade indicator (letters next to each other).
'crew' becomes 'men' (I've seen this before**).
'holding' means one lot of letters goes inside another.
'party' becomes 'do' (do is a kind of party).
'ab'+'men'='abmen'
'abmen' placed around 'do' is 'ABDOMEN'.
(Other definitions for abdomen that I've seen before include "A main part of the body" , "Where one digests" , "Tummy" , "Ban demo (anag)" , "Mean bod (anag.)" .)