Lack of silence in the reading room (3)
I believe the answer is:
din
'lack of silence' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'in the reading room' is the wordplay.
'in' indicates the answer is hidden within the clue.
'DIN' can be found hidden inside 'reading room'.
Can you help me to learn more?
(Other definitions for din that I've seen before include "Loud noise, racket" , "'Loud, harsh noise (3)'" , "Loud annoying noise" , "Row, noise" , "Loud harsh hoise" .)