Childish about smell being severe (8)
I believe the answer is:
inhumane
'severe' is the definition.
Both the definition and answer are adjectives. Perhaps there's a link between them I don't understand?
'childish about smell' is the wordplay.
'childish' becomes 'inane' (inane means silly or childish).
'about' is an insertion indicator.
'smell' becomes 'hum' (something with a bad smell is 'humming').
'inane' enclosing 'hum' is 'INHUMANE'.
'being' acts as a link.
Can you help me to learn more?
(Other definitions for inhumane that I've seen before include "Cruel" , "Callous" , "Heartless" , "Not compassionate" .)