Mark overwhelmed by huge rewards for performing well (6)
I believe the answer is:
oscars
'rewards for performing well' is the definition.
I can't tell whether this definition defines the answer.
'mark overwhelmed by huge' is the wordplay.
'mark' becomes 'scar' (mark left by an injury).
'overwhelmed by' is an insertion indicator (inserted letters get absorbed or overwhelmed).
'huge' becomes 'os' (abbreviation for outsize).
'scar' placed within 'os' is 'OSCARS'.
Can you help me to learn more?
(Other definitions for oscars that I've seen before include "Awards, for dramatic achievements" , "Trophies" , "Movie awards" , "Hollywood annual film awards" , "Hollywood Academy Awards" .)