Swirl (4)
I believe the answer is:
eddy
'swirl' is the definition.
(I know that swirl can be written as eddy)
This is all the clue.
(Other definitions for eddy that I've seen before include "movement going round in circles" , "She founded Christian Science in 1866, d. 1910" , "Christian Scientist" , "Current running against the main stream, causes small whirlpool" , "dangerous bit of water" .)