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