The most common and most likely answer to this crossword clue is the 3 letter word ALI
A
L
I
More clues leading to the result ALI
- Fine setting for Labrador primarily — and boxer
- Boxer’s son ditched by girl?
- Woman abandoned by son, a heavyweight boxer once
- Left cuts excellent boxer
- Old boxer appearing in tabloid regularly
- Even bits of tabloid can be heavyweight
- Noted boxer among finalists
- Boxer knocked over in Sri Lanka
- Boxer making comeback in Manila
- Old fighter entering qualifiers
Buddy explains!

The straight part
We know that "sporting champ" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sporting champ = ali.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.