Mockery made of shortcoming when opener dismissed (9)
I believe the answer is:
imitation
'mockery' is the definition.
(thesaurus)
'shortcoming when opener dismissed' is the wordplay.
'shortcoming' becomes 'limitation' (a limitation is a shortcoming or flaw).
'when opener dismissed' means to remove the first letter (the opening of the word is removed).
'limitation' with its initial letter taken away is 'IMITATION'.
'made of' is the link.
(Other definitions for imitation that I've seen before include "A copy of an authentic item" , "take-off" , "Forgery" , "Sincerest flattery maybe" , "take-off's called for!" .)