For this, there's no payment! (3)
I believe the answer is:
fun
This could be a double definition.
'for this' is the first definition.
The definition suggests a singular noun which matches the answer.
'no payment' is the second definition.
The answer and definition can be both acts as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'there's' acts as a link.
Can you help me to learn more?
(Other definitions for fun that I've seen before include "Jollification" , "Light-hearted amusement, jollity" , "Playful amusement" , "Light-hearted pleasure" , "'Merriment, playfulness (3)'" .)