Burden left to current power (9)
I believe the answer is:
liability
'burden' is the definition.
(thesaurus)
'left to current power' is the wordplay.
'left' becomes 'l' (common abbreviation).
'to current' becomes 'i' (symbol for electric current).
'power' becomes 'ability' ('ability' can be a synonym of 'power'**).
'l'+'i'+'ability'='LIABILITY'
(Other definitions for liability that I've seen before include "Hindrance" , "Indebtedness" , "duty" , "Millstone" , "Debt; drawback" .)