Nag about gold on a fibre (6)
I believe the answer is:
angora
'fibre' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'nag about gold on a' is the wordplay.
'about' indicates an anagram.
'gold' becomes 'or' ('or' is the heraldic name for gold).
'on' says to put letters next to each other.
'nag' with letters rearranged gives 'ang'.
'ang'+'or'+'a'='ANGORA'
Can you help me to learn more?
(Other definitions for angora that I've seen before include "Goat producing mohair" , "Goat prized for its long silky hair" , "Soft yarn from goat" , "Name of goat at 12 Across" , "Breed of rabbit or cat, the former name for the Turkish capital" .)