It's allowed on court (3)
I believe the answer is:
let
This clue might be a double definition.
'it's allowed' is the first definition.
(to let is to allow or permit)
'court' is the second definition.
The answer and definition can be both to do with social activities as well as being verbs in their base form.
Maybe there's an association between them I don't understand?
'on' acts as a link.
Can you help me to learn more?
(Other definitions for let that I've seen before include "Rent out: grant" , "Permitted" , "Allow or rent" , "Permit; lease" , "Permit or rent" .)