Applies, as influence (6)
I believe the answer is:
exerts
'applies as influence' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for exerts that I've seen before include "Brings into use, say strength" , "Forcefully applies (pressure)" , "Makes strenuous effort" , "Brings into use or to bear" , "Makes use of" .)