Indigo lead of neutered dog (5)
I believe the answer is:
dingo
'neutered dog' is the definition.
'dingo' can be an answer for 'dog' (I've seen this before). I'm unsure of the 'neutered' bit.
'indigo lead' is the wordplay.
'indigo' becomes 'din' (I can't justify this - if you can you should believe this answer much more).
'lead' becomes 'go' (synonyms).
'din'+'go'='DINGO'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for dingo that I've seen before include "Wild dog of Oz" , "Wild Australian dog" , "Wild thing" , "dog running wild" , "One running wild in Australia" .)