One brought up to be unchangingly paternal? (3)
I believe the answer is:
dad
'one' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for dad that I've seen before include "Popular and informal father" , "Mum's mate" , "Papa" , "Pa" , "Popular father - a palindrome" .)