Little European swimmer in pond? (7)
I believe the answer is:
tadpole
'swimmer in pond?' is the definition.
'little european' is the wordplay.
'little' becomes 'tad'.
'european' becomes 'pole' (Pole is an example).
'tad'+'pole'='TADPOLE'
(Other definitions for tadpole that I've seen before include "Legless creature" , "young swimmer" , "Future frog maybe" , "Young Kermit" , "A frog-to-be" .)