Work in 'Bill & Ted' took over (7)
I believe the answer is:
adopted
'took over' is the definition.
('adopt' can be a synonym of 'take over')
'work in bill ted' is the wordplay.
'work' becomes 'op' (abbreviation for opus).
'in' means one lot of letters goes inside another.
'bill' becomes 'ad' (advertisement stuck on wall).
'ad'+'ted'='adted'
'op' placed inside 'adted' is 'ADOPTED'.
(Other definitions for adopted that I've seen before include "Taken as one's own" , "Took under one's wing" , "Chose to follow" , "Took into one's family" , "Borrowed" .)