All hands on board get the ship moving (6)
I believe the answer is:
screws
'all hands' is the definition.
The answer and definition can be both acts as well as being plural nouns.
Perhaps you can see a link between them that I can't see?
'on board get the ship moving' is the wordplay.
'on board' becomes 'ss' (I've seen this in other clues).
'get' is an insertion indicator.
'the ship moving' becomes 'crew' (I can't explain this - if you can you should believe this answer much more).
'ss' enclosing 'crew' is 'SCREWS'.
Can you help me to learn more?
(Other definitions for screws that I've seen before include "Put on" , "Fix in place (6)" , "Grooved fastening devices" , "Grooved type of nails" , "Prison warders (sl.)" .)