Take action in accordance with; affect (3,2)
I believe the answer is:
act on
(Other definitions for act on that I've seen before include "Respond in accordance with -- London district (3,2;5)" , "Take notice of" , "-- Bell, pen name of Anne Bronte; W. London area" , "Part of the London borough of Ealing -- British historian, d. 1902" , "Take steps to follow - and affect" .)