Initial friend working on board (5,4)
I believe the answer is:
first mate
'working on board' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'initial friend' is the wordplay.
'initial' becomes 'first' (similar in meaning).
'friend' becomes 'mate' (mate is a kind of friend).
'first'+'mate'='FIRST MATE'
Can you help me to learn more?
(Other definitions for first mate that I've seen before include "sailor?" , "officer on ship" , "Second in command on ship, like primary spouse" , "Eve" , "Ship's officer" .)