Laughing escalates (9)
I believe the answer is:
increases
'escalates' is the definition.
The definition and answer can be both related to change as well as being verbs in their -s form.
Perhaps you can see a link between them that I don't see?
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for increases that I've seen before include "Becomes greater" , "Gets bigger" , "Becomes bigger" .)