Delay robbery (4,2)
I believe the answer is:
hold up
I believe this clue is a double definition.
'delay' is the first definition.
(I know that delay can be written as hold up)
'robbery' is the second definition.
(I know that robbery can be written as hold-up)
(Other definitions for hold up that I've seen before include "Delay" , "Support by arms - threaten by arms" , "Hitch" , "Exhibit" , "lift" .)