Turncoat sailor in Morocco city? (5)
I believe the answer is:
rabat
'morocco city?' is the definition.
(I've seen this in another clue)
'turncoat sailor in' is the wordplay.
'turncoat' becomes 'rat' (I've seen this in another clue).
'sailor' becomes 'ab' (abbreviation for able seaman).
'in' is an insertion indicator.
'rat' placed around 'ab' is 'RABAT'.
(Other definitions for rabat that I've seen before include "capital city" , "N African capital" , "N African city" , "Moroccan city" , "Moroccan capital" .)