However stupid, one can see that private rooms have a key (5)
I believe the answer is:
dense
'however stupid one' is the definition.
Both the definition and answer are adjectives. Perhaps they are linked in a way I don't understand?
'see that private rooms have a key' is the wordplay.
'see that private rooms' becomes 'dens' (den can mean a private hideout).
'have' says to put letters next to each other.
'a key' becomes 'e' (musical key).
'dens'+'e'='DENSE'
'can' acts as a link.
Can you help me to learn more?
(Other definitions for dense that I've seen before include "Not very bright" , "Close-knit" , "Stupid; compacted" , "Closely crowded together" , "Maybe bovine" .)