Deny entry after direction (6)
I believe the answer is:
negate
'deny' is the definition.
(negate can mean to deny or refute)
'entry after direction' is the wordplay.
'entry' becomes 'gate' (I've seen this in another clue).
'after' is a charade indicator (letters next to each other).
'direction' becomes 'ne' (NE is an example).
'gate' put after 'ne' is 'NEGATE'.
(Other definitions for negate that I've seen before include "Contradict" , "Deny the truth of" , "Cause to have no effect" , "Render ineffective" , "Countermand" .)