X is about all right as a symbol (5)
I believe the answer is:
token
'a symbol' is the definition.
(I know that token is a type of symbol)
'x is about all right' is the wordplay.
'x' becomes 'ten' (X is the Roman numeral for ten).
'is about' is an insertion indicator.
'all right' becomes 'ok' (synonyms).
'ten' going around 'ok' is 'TOKEN'.
'as' acts as a link.
(Other definitions for token that I've seen before include "Sign - voucher - chip" , "Shopping voucher" , "Money substitute" , "Counter" , "Nominal - souvenir" .)