More than 500 find poetry varied (7)
I believe the answer is:
diverse
'varied' is the definition.
(I've seen this before)
'more than 500 find poetry' is the wordplay.
'more than 500' becomes 'DI' (Roman numerals for 501).
'find' says to put letters next to each other.
'poetry' becomes 'verse' (synonyms).
'di'+'verse'='DIVERSE'
(Other definitions for diverse that I've seen before include "Revised, being of different kinds" , "Different and various" , "Multifarious" , "Disparate" , "Book" .)