Broken nine-volts circuit (9)
I believe the answer is:
insolvent
'circuit' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'broken nine-volts' is the wordplay.
'broken' indicates an anagram.
'nine'+'volts'='ninevolts'
'ninevolts' is an anagram of 'INSOLVENT'.
Can you help me to learn more?
(Other definitions for insolvent that I've seen before include "without the means to pay" , "strapped for cash" , "In the red" , "on the rocks" , "Broke" .)