One playing grand French song, forgetting opening line (5)
I believe the answer is:
gamer
'french song forgetting opening line' is the definition.
I can't tell whether this definition defines the answer.
'one playing grand' is the wordplay.
I cannot quite understand how this works, but
'one' could be 'me' (a setter might use 'one' to humourously mean 'me') and 'me' is found in the answer.
'grand' could be 'g' (G is short for grand as in a thousand) and 'g' is present in the answer.
The remaining letters 'ar' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for gamer that I've seen before include "One plays" , "More spirited" , "One role-playing on computer" , "One having fun with computer" , "I bet" .)