Tom's turn to provide a saying (5)
I believe the answer is:
motto
'a saying' is the definition.
(I know that motto is a type of saying)
'tom's turn to' is the wordplay.
'turn' is a reversal indicator.
'tom' written backwards gives 'mot'.
'mot'+'to'='MOTTO'
'provide' acts as a link.
(Other definitions for motto that I've seen before include "Words often found on coat of arms" , "Christmas cracker item" , "Slogan encapsulating self-image" , "Adage (found in a cracker?)" , "Guiding adage" .)