Confusion about Inland Revenue going over figure (8)
I believe the answer is:
triangle
'figure' is the definition.
(triangle is a kind of figure)
'confusion about inland revenue going over' is the wordplay.
'confusion' becomes 'tangle' (tangle is a kind of confusion).
'about' indicates putting letters inside.
'inland revenue' becomes 'ir' (abbreviation for Inland Revenue).
'going over' says the letters should be written in reverse.
'ir' backwards is 'ri'.
'tangle' placed around 'ri' is 'TRIANGLE'.
(Other definitions for triangle that I've seen before include "Regular shape with" , "Three-sided polygon" , "Three-sided shape" , "Three-sided figure (maths)" , "kitchen item" .)