A seaman entertaining Nutmeg served up Indian dish (5)
I believe the answer is:
raita
'indian dish' is the definition.
(type of Indian side dish)
'a seaman entertaining nutmeg served up' is the wordplay.
'seaman' becomes 'tar' (Jack Tar is an informal term for a sailor).
'entertaining' means one lot of letters goes inside another.
'nutmeg' becomes 'I' (where the crossword setter is 'Nutmeg').
'served up' says the letters should be written backwards.
'a'+'tar'='atar'
'atar' enclosing 'i' is 'atiar'.
'atiar' in reverse letter order is 'RAITA'.
(Other definitions for raita that I've seen before include "Yoghurt-based Indian condiment" , "Yogurt, chopped cucumber and spices" , "side dish with curry?" , "cooling dish" , "Indian side-dish of cucumber and yoghurt" .)