He's in a whirl (4)
I believe the answer is:
eddy
This clue is a double definition.
'he's' is the first definition.
'a whirl' is the second definition.
(I've seen this before)
'in' is the link.
(Other definitions for eddy that I've seen before include "religious leader" , "Circle around" , "Whirlwind" , "Little swirl in water" , "Whirling current" .)