Engineers have shop to refurbish (7)
I believe the answer is:
restore
'refurbish' is the definition.
(thesaurus)
'engineers have shop' is the wordplay.
'engineers' becomes 're' (Royal Engineers).
'have' means one lot of letters go next to another.
'shop' becomes 'store' ('store' can be a synonym of 'shop').
're'+'store'='RESTORE'
'to' is the link.
(Other definitions for restore that I've seen before include "Repair, put back" , "Bring back; repair" , "Repair, renovate" , "Refurbish" , "Bring back, reinstate" .)