The most common and most likely answer to this crossword clue is the 8 letter word DOYENNES
I've seen this crossword clue in The Daily Telegraph
D
O
Y
E
N
N
E
S
More clues leading to the result DOYENNES
Buddy explains!

The straight part
We know that "Senior ladies" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case senior ladies = doyennes.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 DOYENNES mean?
DOYENNES noun- A female doyen.
- The senior or eldest female member of a group, especially one who is most or highly respected.
- A woman who is highly experienced and knowledgeable in a particular field, subject, or line of work; expert