All hands to mow crop
I believe the answer is:
crew cut
'crop' is the definition.
(I've seen this before)
'all hands to mow' is the wordplay.
'all hands' becomes 'crew' (I've seen this in another clue).
'to mow' becomes 'cut' (I can't justify this - if you can you should give a lot more credence to this answer).
'crew'+'cut'='CREWCUT'
Can you help me to learn more?
(Other definitions for crew cut that I've seen before include "A closely cropped hairstyle" , "result of ship's economy drive?" , "Outcome of airline economy study" , "reduced cover above" , "(Military) hairstyle" .)