The most common and most likely answer to this crossword clue is the 8 letter word DEFENDER
I've seen this crossword clue in The Guardian
D
E
F
E
N
D
E
R
More clues leading to the result DEFENDER
- Postpone introducing objective for back four player?
- Guardian to put off admitting purpose
- . Champion’s objective beset by delay
- Goalie maybe put off guarding goal
- Guardian editor returned with electric guitar
- Back freed after wiggling around bottom
- Guardian‘s to hold back, holding back
- Guardian‘s purpose restricted by delay
- Supporter is to give way about finale
- Challenged champion‘s delay about the final
Buddy explains!

The straight part
We know that "Supporter" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case supporter = defender.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.
What does DEFENDER mean?
DEFENDER noun- Someone who defends people or property
- One of the players whose primary task is to prevent the opposition from scoring
- A fighter who seeks to repel an attack
- A lawyer who represents defendants, especially a public defender; a defense attorney (US) or defence counsel (UK)
- A defendant in a civil action