Former inspector reported Treasury department (9)
I believe the answer is:
exchequer
'treasury department' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'former inspector reported' is the wordplay.
'former' becomes 'ex' (prefix meaning former or onetime).
'inspector' becomes 'checker' (checker is a kind of inspector).
'reported' shows a homophone (sound like).
'checker' sounds like 'chequer'.
'ex'+'chequer'='EXCHEQUER'
Can you help me to learn more?
(Other definitions for exchequer that I've seen before include "National treasury" , "large supply of money" , "Department in charge of a nation's finances" , "Bank of England account" , "Government funding?" .)