Foolish leader going off towards the rear (3)
I believe the answer is:
aft
'towards the rear' is the definition.
(I've seen this before)
'foolish leader going off' is the wordplay.
'foolish' becomes 'daft' (I've seen this in another clue).
'leader going off' means to remove the first letter.
'daft' with its initial letter taken off is 'AFT'.
(Other definitions for aft that I've seen before include "Sternward" , "To the rear on board" , "Toward the stern of a boat" , "Farther back on board" , "Near the stern" .)