Severe wife burning trousers (9)
I believe the answer is:
swingeing
'severe' is the definition.
(I've seen this before)
'wife burning trousers' is the wordplay.
'wife' becomes 'w' (abbreviation).
'burning' becomes 'singeing' (I can't explain this - if you can you should believe this answer much more).
'trousers' means one lot of letters goes inside another (trouser can mean to steal or take).
'w' put into 'singeing' is 'SWINGEING'.
Can you help me to learn more?
(Other definitions for swingeing that I've seen before include "Painfully severe (cuts, fine)" , "Huge" , "Extreme" , "Thumping" .)