They confirm amount spent in RTÉ's epic reproduction (8)
I believe the answer is:
receipts
'they confirm amount spent' is the definition.
The definition suggests an adverb but the answer is not.
'rte's epic reproduction' is the wordplay.
'reproduction' is an anagram indicator.
'rtes'+'epic'='rtesepic'
'rtesepic' with letters rearranged gives 'RECEIPTS'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for receipts that I've seen before include "Cooking instructions once" , "Acknowledgments of payment" , "Notes acknowledging money paid" , "Income, takings" , "proceeds" .)