The most common and most likely answer to this crossword clue is the 8 letter word LADETTES
I've seen this crossword clue in Financial Times
L
A
D
E
T
T
E
S
Buddy explains!
The straight part
We know that "rowdy lasses?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rowdy lasses? = ladettes.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 LADETTES mean?
LADETTES noun- A young woman who behaves in a laddish manner, namely being boisterous and loud and drinking to excess.