Closing time in lifeless bar
I believe the answer is:
deadline
'closing time' is the definition.
The answer and definition can be both related to time as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
'lifeless bar' is the wordplay.
'lifeless' becomes 'dead' ('dead' can be similar in meaning to 'lifeless').
'bar' becomes 'line' (I've seen this in other clues**).
'dead'+'line'='DEADLINE'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for deadline that I've seen before include "Fixed completion date" , "Point in time when something must be completed" , "Time-limit as for journalist's copy" , "Time limit as for journalists filing copy" , "Target time" .)