The most common and most likely answer to this crossword clue is the 6 letter word ABBESS
I've seen this crossword clue in The Guardian
A
B
B
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S
More clues leading to the result ABBESS
- One born Elizabeth to become senior sister
- Sailor girl with unmarried sisters in her care
- Senior ecclesiastic babes travelling south
- Sailor is married to Elizabeth, a superior lady
- Sailor girl, one with unmarried sisters in her care
- Blood type of old queen found in Crewe
- What makes bishop be taken in by idiot woman trying to be religious?
- Sailor is married to Elizabeth — a superior lady
- Sailor Elizabeth became mother superior
- Convent leader has Jack joining Elizabeth
Buddy explains!

The straight part
We know that "a superior lady" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a superior lady = abbess.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 ABBESS mean?
ABBESS noun- A female superior or governess of a nunnery, or convent of nuns, having the same authority over the nuns which the abbots have over the monks.
- (British slang) A woman who runs a brothel; a woman employed by a prostitute to find clients.