Lends support to (4)
I believe the answer is:
aids
'lends support to' is the definition.
(aiding is a kind of lending support to)
This is all the clue.
(Other definitions for aids that I've seen before include "Helps with a dread disease" , "Condition following infection with HIV virus" , "Said to be an international disease" , "Comes to the rescue" , "Assists" .)