Mounting design can go wrong (9)
I believe the answer is:
ascending
'mounting' is the definition.
(thesaurus)
'design can go wrong' is the wordplay.
'go wrong' indicates anagramming the letters.
'design'+'can'='designcan'
'designcan' is an anagram of 'ASCENDING'.
(Other definitions for ascending that I've seen before include "Going up" , "Getting up" , "Rising" .)