Blame left's incompetence, with election finally lost (9)
I believe the answer is:
liability
'blame' is the definition.
(thesaurus)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for liability that I've seen before include "Debt; drawback" , "Hindrance" , "duty" , "Financial obligation" , "Millstone" .)