Champion in great escape (3-6)
I believe the answer is:
top-flight
'champion' is the definition.
'great escape' is the wordplay.
'great' becomes 'top'.
'escape' becomes 'flight' (synonyms).
'top'+'flight'='TOP-FLIGHT'
'in' is the link.
(Other definitions for top-flight that I've seen before include "Superior" , "Highest level" , "Excellent -- best possible" , "Of the highest class" .)