Exhibits left onboard (6)
I believe the answer is:
sports
'exhibits' is the definition.
'left onboard' is the wordplay.
I cannot quite see how this works, but
'left' could be 'port' (left side of a ship - opposite of starboard) and 'port' is located in the answer.
This may be the basis of clue (or it may be nonsense).
(Other definitions for sports that I've seen before include "Soccer and rugby, say" , "Eg, football, tennis" , "Wears (a noticeable item)" , "plays" , "like a day at school" .)