Do call (8)
I believe the answer is:
occasion
I believe this clue is a double definition.
'do' is the first definition.
(I know that occasion is a type of do)
'call' is the second definition.
(I've seen this before)
(Other definitions for occasion that I've seen before include "Make happen" , "Give rise to" , "Opportunity" , "Time of (maybe special) event" , "Special event; reason" .)