Abandonment bringing about Tories' end (9)
I believe the answer is:
desertion
'abandonment' is the definition.
(I know that abandonment can be written as desertion)
'about tories' end' is the wordplay.
'about' indicates an anagram.
'tories'+'end'='toriesend'
'toriesend' with letters rearranged gives 'DESERTION'.
'bringing' is the link.
(Other definitions for desertion that I've seen before include "going AWOL" , "Abandonment" , "flight" .)