Strongly against (4)
I believe the answer is:
anti
'strongly against' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for anti that I've seen before include "Hostile" , "An opponent - opposed to party policy, etc" , "Who pooh-poohs all" , "(Person who is) not in favour" , "one opposing?" .)