Caught many a poor reptile (6)
I believe the answer is:
cayman
'reptile' is the definition.
(cayman is a kind of reptile)
'caught many a poor' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'poor' indicates anagramming the letters.
'many'+'a'='manya'
'manya' with letters rearranged gives 'ayman'.
'c'+'ayman'='CAYMAN'
(Other definitions for cayman that I've seen before include "Fearsome creature" , "Aquatic reptile" , "Alligator - island" , "Alligator-like reptile; Amy can (anagram)" , "Alligator relative" .)