Glutton welcomes embracing start of diet -- funny guy! (6,4)
I believe the answer is:
greedy guts
'glutton' is the definition.
(both can mean a greedy person)
'welcomes embracing start of diet funny guy' is the wordplay.
'welcomes' becomes 'greets' (I've seen this in another clue).
'embracing' indicates putting letters inside.
'start of' suggests taking the first letters.
'funny' indicates anagramming the letters.
The first letter of 'diet' is 'd'.
'guy' anagrammed gives 'ygu'.
'd'+'ygu'='dygu'
'greets' going around 'dygu' is 'GREEDY GUTS'.
(Other definitions for greedy guts that I've seen before include "Pig" , "Excessive eater" .)