Brother of one of the Seven Sisters? (5)
I believe the answer is:
cliff
'brother of one of the seven sisters?' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
This is the entire clue.
Can you help me to learn more?
(Other definitions for cliff that I've seen before include "High, steep rock face" , "stony face?" , "Precipice" , "A steep rock-face on coast" , "A sheer rock-face" .)