Friend working on board (4)
I believe the answer is:
mate
'friend' is the definition.
(I know that mate is a type of friend)
'working on board' is the wordplay.
I cannot quite see how this works, but
'on' could be 'at' (I've seen this in other clues) and 'at' is found within the answer.
The remaining letters 'me' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for mate that I've seen before include "Sailor" , "Better half" , "Companion, wife" , "One of a pair or a pal" , "Marry - friend" .)