Where the bright lights are left burning, we assume? (6)
I believe the answer is:
london
'where the bright lights are left burning' is the definition.
The answer is a location as well as being a singular noun. This is suggested by the definition.
'we assume?' is the wordplay.
'we' becomes 'lon' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'assume?' becomes 'don' (I've seen this in another clue).
'lon'+'don'='LONDON'
Can you help me to learn more?
(Other definitions for london that I've seen before include "Home of Cockney" , "Where Boris Johnson might be" , "British capital" , "US writer" , "- Clay; - pride; - plane" .)