Went off embarrassed having eaten too much (6)
I believe the answer is:
rotted
'went off' is the definition.
'embarrassed having eaten too much' is the wordplay.
'embarrassed' becomes 'red' (I've seen this before).
'having eaten' means one lot of letters goes inside another.
'too much' becomes 'ott' (short for 'over the top' - informal British).
'red' enclosing 'ott' is 'ROTTED'.
(Other definitions for rotted that I've seen before include ".Decayed, decomposed" , "Having decayed or corroded" .)