The most common and most likely answer to this crossword clue is the 10 letter word TOUCHSTONE
I've seen this crossword clue in Financial Times
T
O
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C
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More clues leading to the result TOUCHSTONE
- Jasper, perhaps a jester
- Solicit a few pounds for Audrey’s husband
- Time that was painful – intially sullen manner becomes standard
- The standard by which to judge a witty fool say
- Standard Shakespearean jester
- Move weight, creating criterion
- Criterion’s where you’ll see someone in As You Like It
- Sense mood to accept second criterion
- Standard type of telephone around South
Buddy explains!

The straight part
We know that "Jasper/perhaps a jester" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case jasper/perhaps a jester = touchstone.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 TOUCHSTONE mean?
TOUCHSTONE noun- A stone used to check the quality of gold alloys by rubbing them to leave a visible trace.
- (by extension) A standard of comparison or evaluation.