Stiff, while the previous one had a nice flexible cover (9)
I believe the answer is:
inelastic
'stiff' is the definition.
(I've seen this before)
'while the previous one had a nice flexible cover' is the wordplay.
I cannot quite see how this works, but
'while' could be 'as' and 'as' is found in the answer.
'one' could be 'i' (Roman numeral) and 'i' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for inelastic that I've seen before include "lacking resilience" , "Not giving" , "Rigid" , "stiff" , "Without a spring" .)