Cart reversed three feet (4)
I believe the answer is:
dray
'cart' is the definition.
(a cart without sides for delivering heavy loads)
'reversed three feet' is the wordplay.
'reversed' shows that the letters should be reversed in order.
'three feet' becomes 'yard' (I've seen this in another clue).
'yard' in reverse letter order is 'DRAY'.
(Other definitions for dray that I've seen before include "Draught horse" , "Delivery cart" , "Brewery wagon" , "Flat-bed truck" , "Heavy load-carrying vehicle" .)