Pond creatures requiring little rods (8)
I believe the answer is:
tadpoles
'pond creatures' is the definition.
(tadpoles might live in ponds)
'little rods' is the wordplay.
'little' becomes 'tad' (both can mean a small amount).
'rods' becomes 'poles' (pole is a kind of rod).
'tad'+'poles'='TADPOLES'
'requiring' is the link.
(Other definitions for tadpoles that I've seen before include "Immature frogs" , "Pond-life" , "Little swimmers" , "Larval frogs" , "Larvae of frogs or toads" .)