This instant wicket comes after not out (3)
I believe the answer is:
now
'this instant' is the definition.
(I've seen this in another clue)
'wicket comes after not out' is the wordplay.
'wicket' becomes 'w'.
'comes after' is a charade indicator (letters next to each other).
'out' means to remove the last letter.
'not' with its final letter taken off is 'no'.
'w' put after 'no' is 'NOW'.
(Other definitions for now that I've seen before include "At the present time" , "Immediately" , "At this moment in time" , "The present moment" , "Today" .)