Mice bile concoction for fool (8)
I believe the answer is:
imbecile
'fool' is the definition.
(I've seen this before)
'mice bile concoction' is the wordplay.
'concoction' indicates anagramming the letters.
'mice'+'bile'='micebile'
'micebile' anagrammed gives 'IMBECILE'.
'for' acts as a link.
(Other definitions for imbecile that I've seen before include "Dolt" , "fool" , "Jerk" , "Charlie" , "Sap" .)