Parrot detailed answers defending atrocious act (9)

'parrot' is the definition.
Although both the answer and definition are verbs in their base form, I don't understand how they can define each other.

'detailed answers defending atrocious act' is the wordplay.
'detailed' means to remove the last letter (the tail of the word is removed).
'answers' becomes 'replies' (to reply is to give an answer).
'defending' means one lot of letters goes inside another (inserted letters are defended).
'atrocious' is an anagram indicator.
'replies' with its final letter taken off is 'replie'.
'act' anagrammed gives 'cat'.
'replie' placed around 'cat' is 'REPLICATE'.

Can you help me to learn more?