Cart is moved back three feet (4)
I believe the answer is:
dray
'cart' is the definition.
(a cart without sides for delivering heavy loads)
'back three feet' is the wordplay.
'back' shows that the letters should be reversed in order.
'three feet' becomes 'yard' (I've seen this before).
'yard' backwards is 'DRAY'.
'is moved' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for dray that I've seen before include "Brewery wagon" , "Strong low cart for heavy loads" , "Cart to carry heavy loads" , "Cart for carrying heavy goods" , "Flat-bed truck" .)