Puts pressure on the men who sail in a ship (6)
I believe the answer is:
screws
'puts pressure on' is the definition.
I can't judge whether this defines the answer.
'men who sail in a ship' is the wordplay.
I cannot quite see how this works, but
'men' could be 'crew' (I've seen this in other clues) and 'crew' is present in the answer.
'ship' could be 'ss' (prefix in ship names eg SS Great Britain) and 'ss' is present in the leftover letters.
No letters remain.
This explanation may well be incorrect...
'the' is the link.
Can you help me to learn more?
(Other definitions for screws that I've seen before include "Fix in place (6)" , "Pins with spiral threads" , "Fasteners with threaded shanks" , "Fastening devices and prison guards, colloquially" , "Put on" .)