Lie has fooled Dicky (9)
I believe the answer is:
falsehood
'lie' is the definition.
(I've seen this before)
'has fooled dicky' is the wordplay.
'dicky' indicates anagramming the letters (dicky can mean ill or non-functioning).
'has'+'fooled'='hasfooled'
'hasfooled' with letters rearranged gives 'FALSEHOOD'.
(Other definitions for falsehood that I've seen before include "Has fooled with lie" , "Untruth" , "Fictional account" , "Deception" , "Pork pie" .)