Occupy during routine (7)
I believe the answer is:
inhabit
'occupy' is the definition.
(I know that occupy is a more specific form of inhabit)
'during routine' is the wordplay.
'during' becomes 'in' (e.g. during February means in February).
'routine' becomes 'habit' (I've seen this before).
'in'+'habit'='INHABIT'
(Other definitions for inhabit that I've seen before include "Live in (a place)" , "Occupy (dwelling)" , "Dwell in" , "Tenant" , "Occupy - settle" .)