The most common and most likely answer to this crossword clue is the 7 letter word TONSURE
I've seen this crossword clue in The Times
T
O
N
S
U
R
E
More clues leading to the result TONSURE
- Haircut not raised, certainly
- Certain to follow fashion that's very different from dreadlocks!
- Feature of monastic life certainly after Mass
- Large amount, definitely brother’s cut
- Fashion with certain style for monks
- Characteristic of monk to start to swim in northern river
- Cut on head: not upset? Absolutely
- Heavyweight certain to display shaven head
- True son in order shows sign of being a monk
- Haircut 100, of course!
Buddy explains!

The straight part
We know that "brother’s cut" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case brother’s cut = tonsure.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 TONSURE mean?
TONSURE noun- A ritual shaving of this kind.
- The bald patch resulting from being tonsured.
- To shave the crown of the head as a sign of humility and religious vocation.