Kay is satisfied with fate (6)
I believe the answer is:
kismet
'fate' is the definition.
(kismet is a kind of fate)
'kay is satisfied' is the wordplay.
'kay' becomes 'k'.
'satisfied' becomes 'met' ('meet' can be a synonym of 'satisfy').
'k'+'is'+'met'='KISMET'
'with' acts as a link.
(Other definitions for kismet that I've seen before include "Fate - 1953 musical" , "Will of Allah" , "Turkish fate, destiny" , "Broadway musical" , "fortune" .)