Large portion? It may be too much (1,3,2,4,5)
I believe the answer is:
a lot on ones plate
'large portion? it may' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'too much' is the wordplay.
I cannot really see how this works, but
an anagram of 'too' is 'oto' which is present in the answer.
This explanation may well be incorrect...
'be' is the link.
Can you help me to learn more?
(Other definitions for a lot on ones plate that I've seen before include "A glutton will have this" , "busy people too" .)