Setter on board ship in dining room (4)
I believe the answer is:
mess
'ship in dining room' is the definition.
'mess' can be an answer for 'room' (mess is a kind of room). I'm unsure of the 'ship in dining' bit.
'setter on board' is the wordplay.
'setter' becomes 'me' (the setter of the clue).
'on board' becomes 'ss' (I've seen this in other clues).
'me'+'ss'='MESS'
Can you help me to learn more?
(Other definitions for mess that I've seen before include "Disagreeable mixture" , "Food-hall" , "Place to eat" , "Military dining room" , "Military dining area" .)