What does the cryptic crossword clue "Reward announced for each returned book (9)" mean?

The definition is "book". The wordplay uses a homophone (sounds like). Homophone of “pay” + PER (for each) + BACK (returned) The answer is PAPERBACK.

Reward announced for each returned book (9)

Guardian Cryptic #29681 | 9 Across | 2025-04-29 flower