The most common and most likely answer to this crossword clue is the 8 letter word PARTISAN
I've seen this crossword clue in The Times
P
A
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T
I
S
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More clues leading to the result PARTISAN
- Resistance fighter trained in Sparta
- Quiet craftsman, biased
- Zealot engaged in pop art is antagonistic
- Unfair, putting pressure on manual worker
- Pressure put on skilled worker, resistance fighter
- Quiet craftsman is prejudiced
- Guerrilla, creative type after power
- Irregular power worker
- Biased worker going after power
- Raves where ecstasy’s dropped by an underground warrior
Buddy explains!

The straight part
We know that "Zealot" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case zealot = partisan.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 PARTISAN mean?
PARTISAN noun- An adherent to a party or faction.
- A fervent, sometimes militant, supporter or proponent of a party, cause, faction, person, or idea.
- A member of a band of detached light, irregular troops acting behind occupying enemy lines in the ways of harassment or sabotage; a guerrilla fighter.
- The commander of a body of detached light troops engaged in making forays and harassing an enemy.
- Serving as commander or member of a body of detached light troops.
- Adherent to a party or faction; especially, having the character of blind, passionate, or unreasonable adherence to a party.
- Devoted to or biased in support of a party, group, or cause.
- A long-handled spear with a triangular, double-edged blade having lateral projections, in some forms also used in boar hunting.
- A soldier armed with such a weapon.