Doesn't go to sleep on board ship (5)
I believe the answer is:
skips
'doesn't go to' is the definition.
(I've seen this in another clue)
'sleep on board ship' is the wordplay.
'sleep' becomes 'kip' (synonyms).
'on board' indicates putting letters inside (inserted letters are taken on board).
'ship' becomes 'SS' (prefix in ship names eg SS Great Britain).
'kip' inserted into 'ss' is 'SKIPS'.
(Other definitions for skips that I've seen before include "Waste containers" , "Large containers for rubbish" .)