Not made a meal of, bighead leaves undefeated (7)
I believe the answer is:
uneaten
'not made a meal' is the definition.
I can't judge whether this defines the answer.
'bighead leaves undefeated' is the wordplay.
'bighead' becomes 'b' (the head letter of 'big').
'leaves' indicates named letters should be taken away.
'undefeated' becomes 'unbeaten' (similar in meaning).
'unbeaten' with 'b' taken out is 'UNEATEN'.
'of' is the link.
Can you help me to learn more?
(Other definitions for uneaten that I've seen before include "not chewed" , "Left after dinner" , "still on the table?" , "Left on the plate" , "Make an outline of" .)