A foot at the rear of a ship (3)
I believe the answer is:
'rear of a ship' is the definition.
'aft' can be an answer for 'rear' (I've seen this in another clue). I am not sure about the 'of a ship' bit.
'a foot at the' is the wordplay.
'foot' becomes 'f' (abbreviation).
'at' says to put letters next to each other.
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
Can you help me to learn more?
(Other definitions for aft that I've seen before include "Of ship, fat in the rear" , "back to sailors" , "towards the end" , "Rear part" , "Near the rear (of ship)" .)