Having a crush on, show affection (3)
I believe the answer is:
hug
'show affection' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for hug that I've seen before include "Tightly embrace" , "A hearty embrace as of bear" , "Embrace closely" , "Clasp" , "Tight embrace" .)