Just the place for having fun (4)
I believe the answer is:
fair
'just' is the definition.
(just can mean fair in the sense of showing justice)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for fair that I've seen before include "likely" , "Just; amusement" , "Unbiased, being light of skin" , "Blonde or equitable" , "Pretty; impartial" .)