About to smack, intercepted (3,3)
I believe the answer is:
cut off
'intercepted' is the definition.
(I've seen this before)
'about to smack' is the wordplay.
'about' means one lot of letters goes inside another.
'smack' becomes 'cuff' (both can mean to hit).
'to' inserted within 'cuff' is 'CUT-OFF'.
(Other definitions for cut off that I've seen before include "Designated limit" , "End abruptly" , "Point after which something is no longer effective" , "Disinherit c" , "Device that terminates the flow in a pipe" .)