Way to stuff a European champion (7)
I believe the answer is:
apostle
'champion' is the definition.
(apostle is a kind of champion)
'way to stuff a european' is the wordplay.
'way' becomes 'st' (**).
'to stuff' means one lot of letters goes inside another.
'european' becomes 'pole' (Pole is an example).
'a'+'pole'='apole'
'st' going inside 'apole' is 'APOSTLE'.
(Other definitions for apostle that I've seen before include "Religious messenger" , "Vigorous campaigner" , "Divine messenger" , "James, perhaps" , "Originally, one sent to preach the gospel" .)