Small toothed whale (7)
I believe the answer is:
dolphin
'small toothed whale' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for dolphin that I've seen before include "member in school" , "Snall type of whale" , "Bottlenose creature?" , "Sea-mammal" , "Sociable sea mammal, sacred in ancient Greece" .)