He stole on board (6)
I believe the answer is:
pirate
'stole on board' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'he' is the wordplay.
I cannot quite see how this works, but
'he' could be 'ira' and 'ira' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for pirate that I've seen before include "sailor" , "Captain Hook, say" , "Run off without permission" , "Illegally-copied (version)" , "Use (another's work) for profit without permission" .)