Ladies perhaps passed round drink endlessly (7)
I believe the answer is:
latrine
'ladies perhaps' is the definition.
I can't judge whether this defines the answer.
'passed round drink endlessly' is the wordplay.
'passed' becomes 'late' (I can't explain this - if you can you should give a lot more credence to this answer).
'round' is an insertion indicator.
'endlessly' says to take the centre (the ends of the words are removed).
The central letters of 'drink' are 'rin'.
'late' enclosing 'rin' is 'LATRINE'.
Can you help me to learn more?
(Other definitions for latrine that I've seen before include "Camp lavatory" , "where to go in the army" , "Army lavatory" , "A military lavatory" , "waste disposal unit" .)