Apply gently (3)
I believe the answer is:
dab
'apply gently' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for dab that I've seen before include "Apply light touches of colour to the fish" , "A fish; light touch" , "Bad sort of small fish" , "A bad, backward fish" , "Light stroke" .)