Stewardesses so polite holding back berserk (9)
I believe the answer is:
possessed
'berserk' is the definition.
(synonyms)
'stewardesses so polite holding back' is the wordplay.
'holding' indicates the answer is hidden within the clue.
'back' says the letters should be written in reverse.
'dessessop' is hidden in the letters of 'stewardesses so polite'.
'dessessop' written backwards gives 'POSSESSED'.
(Other definitions for possessed that I've seen before include "held as property" , "Bore" , "Demented" , "in need of bell, book and candle" , "Owned - by evil spirit?" .)