Sail support three feet long? (7)
I believe the answer is:
yardarm
'sail' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'support three feet long?' is the wordplay.
I cannot really see how this works, but
'support' could be 'arm' (arm is a kind of support) and 'arm' is found in the answer.
'feet' could be 'yard' (I have seen 'several feet' mean 'yard' so perhaps 'feet' could also mean 'yard') and 'yard' is found in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for yardarm that I've seen before include "Ship's beam" , "Part of ship's mast" , "End of mast's beam" , "Beam on board" , "End of spar on ship's mast" .)