Instant, occurring without delay (9)
I believe the answer is:
immediate
I believe this clue is a double definition.
'instant' is the first definition.
(I've seen this in another clue)
'occurring without delay' is the second definition.
(I've seen this before)
(Other definitions for immediate that I've seen before include "Instant" , "Prompt,straightaway" , "Occurring without delay" , "Most urgent; current" , "Involving no delay" .)