Agent’s hearty turn with fiction writer to buy back (10)

'buy back' is the definition.
'repurchase' can be an answer for 'buy' (thesaurus). I am not certain of the 'back' bit.

'agent's hearty turn with fiction writer' is the wordplay.
I cannot really understand how this works, but
'turn' could be 'u' (a 'U-turn' is a kind of turn) and 'u' is found within the answer.
'agent' could be 'rep' (short for representative) and 'rep' is found in the answer.
This explanation may well be incorrect...

'to' acts as a link.

Can you help me to learn more?