Greedy guts allowed to be Pooh’s friend (6)
I believe the answer is:
piglet
'be pooh's friend' is the definition.
(friend of Winnie the Pooh)
'greedy guts allowed' is the wordplay.
'greedy guts' becomes 'pig' (both can mean a greedy person).
'allowed' becomes 'let' (I've seen this before).
'pig'+'let'='PIGLET'
'to' is the link.
(Other definitions for piglet that I've seen before include "Young porker" , "One with home in Hundred Acre Wood" , "Little creature" , "19's little friend" , "One of Christopher Robin's animals" .)