Fake ring — the ultimate in chicanery (6)
I believe the answer is:
phoney
'fake' is the definition.
(I know this)
'ring the ultimate in chicanery' is the wordplay.
'ring' becomes 'phone' (synonyms).
'the ultimate in' says to take the final letters.
The final letter of 'chicanery' is 'y'.
'phone'+'y'='PHONEY'
(Other definitions for phoney that I've seen before include "Sham or insincere" , "Fraudulent" , "Fraud" , "Bogus" , "Fake, misleading" .)