Support for champ, finally (4)
I believe the answer is:
prop
'support' is the definition.
(prop is a kind of support)
'for champ finally' is the wordplay.
'for' becomes 'pro' (as in being 'pro' something).
'finally' says to take the final letters.
The last letter of 'champ' is 'p'.
'pro'+'p'='PROP'
(Other definitions for prop that I've seen before include "Hold (up), support" , "Set piece" , "Portable film set item" , "Front row forward" , "Temporary support" .)