Little whirlpool (4)
I believe the answer is:
eddy
'little whirlpool' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for eddy that I've seen before include "Vortex" , "(Of fluid) circle round" , "making the rounds?" , "Little swirl in water" , "Miniature whirlpool" .)