There's a vacancy for a start (7)
I believe the answer is:
opening
I believe this clue is a double definition.
'there's a vacancy' is the first definition.
(thesaurus)
'a start' is the second definition.
(opening is a kind of start)
'for' acts as a link.
(Other definitions for opening that I've seen before include "Rent" , "Hole; beginning" , "Window of opportunity" , "Beginning, available job" , "Yawning" .)