Number for five-a-side? Any number is required for game (6)
I believe the answer is:
tennis
'for game' is the definition.
(tennis is a game)
'number for five-a-side? any number is' is the wordplay.
'number' becomes 'n' (n can represent any number).
'for' is a charade indicator (letters next to each other) (I've seen this in other clues).
'five-a-side?' becomes 'te' (I can't explain this - if you can you should believe this answer much more).
'any number' becomes 'n' (mathematical symbol for an unspecified number).
'n' put after 'te' is 'ten'.
'ten'+'n'+'is'='TENNIS'
'required' acts as a link.
Can you help me to learn more?
(Other definitions for tennis that I've seen before include "Game, orig. sphairistike" , "Sent in (anag.)" , "Game played with racquets" , "Sent in, oddly, to play a sport" , "Sport on a court" .)