The most common and most likely answer to this crossword clue is the 10 letter word SEAÂ BREEZE
I've seen this crossword clue in The Guardian
S
E
A
Â
B
R
E
E
Z
E
Buddy explains!

The straight part
We know that "a blow for Brighton" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a blow for brighton = sea breeze.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.