Affects, when one applies it (4,2)
I believe the answer is:
puts on
'affects' is the definition.
The definition and answer can be both related to bodily activities as well as being verbs in their -s form.
Maybe they are linked in a way I don't understand?
'when one applies it' is the wordplay.
I cannot really understand how this works, but
'when' could be 'on' (I've seen this in other clues) and 'on' is located in the answer.
'applies' could be 'puts' (putting is a kind of applying) and 'puts' is located in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Another definition for puts on that I've seen is " Dons".)