Champ's first painful moves in important match (3,5)
I believe the answer is:
cup final
'important match' is the definition.
'cup final' can be an answer for 'match' (cup final is a kind of match). I'm not sure about the 'important' bit.
'champ's first painful moves' is the wordplay.
'champ's first' becomes 'c' (1st letter of 'champ').
'moves' is an anagram indicator.
'painful' anagrammed gives 'upfinal'.
'c'+'upfinal'='CUP-FINAL'
'in' is the link.
Can you help me to learn more?
(Other definitions for cup final that I've seen before include "Last match in a knockout football competition" , "Last fixture in the competition?" , "Last game in an FA knockout tournament" , "Last footballing tie" , "Last important game" .)