WWII alliance (4)
I believe the answer is:
axis
'wwii alliance' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for axis that I've seen before include "Imaginary line around which a body rotates" , "WW2 Nazi alliance" , "Spotted deer" , "all revolves around this" , "Spindle - German/Italian alliance - deer" .)