One making a total season (6)
I believe the answer is:
summer
'season' is the definition.
(summer is a season)
'one making a total' is the wordplay.
I cannot really see how this works, but
'one' could be 'me' (a setter might use 'one' to humourously mean 'me') and 'me' is found within the answer.
'total' could be 'sum' (synonyms) and 'sum' is located in the answer.
A single letter 'r' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for summer that I've seen before include "warm spell" , "One making the whole" , "Late singer" , "Warmest season" , "One adding up" .)