Helps, assists (4)
I believe the answer is:
aids
This clue is a double definition.
'helps' is the first definition.
('aid' can be a synonym of 'help')
'assists' is the second definition.
('aid' can be a synonym of 'assist')
(Other definitions for aids that I've seen before include "Comes to the rescue" , "Said to be a modern plague" , "Assists" , "Condition following infection with HIV virus" , "Said to be a dread modern disease" .)