Completely revamp and halve our working (8)
I believe the answer is:
overhaul
'completely revamp' is the definition.
(to overhaul is to redesign completely)
'halve our working' is the wordplay.
'working' indicates anagramming the letters.
'halve'+'our'='halveour'
'halveour' with letters rearranged gives 'OVERHAUL'.
'and' is the link.
(Other definitions for overhaul that I've seen before include "Recondition" , "Examine and repair (machinery)" , "Renovate, maintain" , "Check-up" , "Inspect and repair" .)