The sloping walkway got older and behaved shockingly badly (8)
I believe the answer is:
rampaged
'behaved shockingly badly' is the definition.
I can't tell whether this definition defines the answer.
'the sloping walkway got older' is the wordplay.
'the sloping walkway' becomes 'ramp' (I've seen this before).
'got older' becomes 'aged' ('age' can be a synonym of 'get older').
'ramp'+'aged'='RAMPAGED'
'and' acts as a link.
Can you help me to learn more?
(Other definitions for rampaged that I've seen before include "ran amok" , "Went berserk" , "Charged" , "ran riot" , "Rushed wildly" .)