Do up (8)
(Other definitions for restore that I've seen before include "Strengthen" , "Bring back to original state" , "Repair, put back" , "Cure" , "Refurbish" .)
(Other definitions for tighten that I've seen before include "Make stricter" , "Make tenser" , "Apply increased tension or security" , "Give an extra turn" , "Make tauter" .)
'do up' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for renovate that I've seen before include "Restore to a good state of repair" , "Restore (something old)" , "Restore to a previous or better condition" , "Make as new" , "Bring back to pristine condition" .)