Start to vacate it, possibly (8)
I believe the answer is:
activate
'start' is the definition.
(I've seen this before)
'vacate it possibly' is the wordplay.
'possibly' indicates anagramming the letters.
'vacate'+'it'='vacateit'
'vacateit' with letters rearranged gives 'ACTIVATE'.
'to' is the link.
(Other definitions for activate that I've seen before include "Cause to start, set in motion" , "Give life to" , "Turn on" , "Make operative" , "Stimulate to action" .)