Frog larva (7)
I believe the answer is:
tadpole
'frog larva' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for tadpole that I've seen before include "being hatched in a puddle?" , "Aquatic larva of frog or toad" , "Amphibian larva" , "Young frog" , "Baby amphibian" .)