Put back record left in competition (7)
I believe the answer is:
replace
'put back' is the definition.
('replace' can be a synonym of 'put back')
'record left in competition' is the wordplay.
'record' becomes 'ep'.
'left' becomes 'l' (common abbreviation).
'in' indicates putting letters inside.
'competition' becomes 'race' (race is a kind of competition**).
'ep'+'l'='epl'
'epl' placed inside 'race' is 'REPLACE'.
(Other definitions for replace that I've seen before include "Substitute for (someone)" , "Provide a substitute for" , "succeed" , "Put back where you found it" , "Put back or substitute" .)