The most common and most likely answer to this crossword clue is the 5 letter word WHIRL
I've seen this crossword clue in The Guardian
W
H
I
R
L
Buddy explains!

The straight part
We know that "trial/spin" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case trial/spin = whirl.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 WHIRL mean?
WHIRL noun- An act of whirling.
- Something that whirls.
- A confused tumult.
- A rapid series of events.
- Dizziness or giddiness.
- (usually following “give”) A brief experiment or trial.
- To rotate, revolve, spin or turn rapidly.
- To have a sensation of spinning or reeling.
- To make something or someone whirl.
- To remove or carry quickly with, or as with, a revolving motion; to snatch.