The most common and most likely answer to this crossword clue is the 6 letter word PERMIT
I've seen this crossword clue in The Times
P
E
R
M
I
T
More clues leading to the result PERMIT
- Deal with unruly hair thus, OK?
- Allow stylist might treat hair thus?
- Agree to what one might do to unruly hair
- Pass quiet loner in the East End?
- Document what one might do with one's hair?
- Pass instruction on how to make hair curl
- Pass through university
- Authorisation for each American university
- Authorise what to do with straight hair for a change?
- Pass by Grant
Buddy explains!

The straight part
We know that "Pass" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case pass = permit.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 PERMIT mean?
PERMIT noun- An artifact or document rendering something allowed or legal.
- Formal permission.
- To allow (something) to happen, to give permission for.
- To allow (someone) to do something; to give permission to.
- To allow for, to make something possible.
- To allow, to admit (of).
- (pronounced like noun) To grant formal authorization for (something).
- (pronounced like noun) To attempt to obtain or succeed in obtaining formal authorization for (something).
- To hand over, resign (something to someone).
- A pompano of the species Trachinotus falcatus.