Small whirlpool (4)
![Ross](/clue/static/ross-mug.min.png)
'small whirlpool' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for eddy that I've seen before include "Small circular movement of water" , "Founder of Christian Science, d. 1910" , "Whirl (in fluid)" , "Swirl; small whirlpool" , "religious leader" .)