Shock to include extremely risible clothing (7)
I believe the answer is:
apparel
'clothing' is the definition.
(I know that clothing can be written as apparel)
'shock to include extremely risible' is the wordplay.
'shock' becomes 'appal' (synonyms).
'to include' indicates putting letters inside.
'extremely' says to hollow out the word (remove centre letters) (letters on the extremes of the word are used).
'risible' with its middle taken out is 're'.
'appal' enclosing 're' is 'APPAREL'.
(Other definitions for apparel that I've seen before include "Clothing, things to wear" , "whatever people have on" , "Real pap (anag) - clothing" , "Formal word for clothing" , "formal dress?" .)