Headless toy bear in a whirl? (4)
I believe the answer is:
eddy
'a whirl?' is the definition.
(I know that eddy can be written as eddy)
'headless toy bear' is the wordplay.
'headless' means to remove the first letter.
'toy bear' becomes 'teddy' (teddy bear).
'teddy' with its initial letter removed is 'EDDY'.
'in' is the link.
(Other definitions for eddy that I've seen before include "current running back" , "A small whirl of water" , "Founder of sect" , "Counter-current" , "Circle around" .)