Discourages, dissuades (6)
I believe the answer is:
deters
I believe this is a double definition.
'discourages' is the first definition.
('deter' can be a synonym of 'discourage')
'dissuades' is the second definition.
('deter' can be a synonym of 'dissuade')
(Other definitions for deters that I've seen before include "is discouraging" , "Persuades or discourages from doing" , "Discourages, dissuades" , "Puts off" , "Discourages or prevents from doing something" .)