Fleet being on mountain top where concubines are (5)
I believe the answer is:
harem
'concubines are' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'fleet being on mountain top' is the wordplay.
I cannot really see how this works, but
'on' could be 're' ('on' can be mean 'with reference to') and 're' is present in the answer.
'being' could be 'ham' (ham is a kind of being) and 'ham' is located in the remaining letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'where' acts as a link.
Can you help me to learn more?
(Other definitions for harem that I've seen before include "Quarters for women in Muslim household, a seraglio" , "Collection of wives, concubines and female servants" , "Living quarters for wives and concubines" , "Court ladies" , "Place for wives of 25 ac" .)