What the crowd would do at the Den? (4)
I believe the answer is:
roar
'what the crowd would do at the den?' is the definition.
The definition suggests a singular noun which matches the answer.
This is the entire clue.
Can you help me to learn more?
(Other definitions for roar that I've seen before include "Cry (as a lion)" , "Loud cry" , "cheer" , "Lion's cry" , "Lion's noise" .)