The most common and most likely answer to this crossword clue is the 8 letter word BARRETTE
B
A
R
R
E
T
T
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More clues leading to the result BARRETTE
Buddy explains!

The straight part
We know that "fix for hair" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fix for hair = barrette.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 BARRETTE mean?
BARRETTE noun- A clasp or clip for gathering and holding the hair.
- To put (hair) into a barrette.
- The lower part of the epimeron.