Birds greedily eat one's nuts (7)
I believe the answer is:
pigeons
'birds' is the definition.
(pigeon is a kind of bird)
'greedily eat one's nuts' is the wordplay.
'greedily eat' becomes 'pig' (pigging is a kind of eating. I am not sure about the 'greedily' bit.).
'nuts' indicates an anagram (nuts can mean crazy).
'ones' anagrammed gives 'eons'.
'pig'+'eons'='PIGEONS'
Can you help me to learn more?
(Other definitions for pigeons that I've seen before include "Type of type or nose" , "Town birds" , "Columbiform birds" , "traditional pie filling" , "Cooing birds" .)