Sadly ruins cane cover (9)
I believe the answer is:
insurance
'cover' is the definition.
(I've seen this before)
'sadly ruins cane' is the wordplay.
'sadly' indicates anagramming the letters.
'ruins'+'cane'='ruinscane'
'ruinscane' is an anagram of 'INSURANCE'.
(Other definitions for insurance that I've seen before include "Protection against a future eventuality" , "Cover against mishaps" , "Cover against misfortune" , "Promise of reimbursement in the case of loss" , "Indemnity" .)