Fault-finding electricians seen leaving (8)
I believe the answer is:
critical
'fault-finding' is the definition.
(thesaurus)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for critical that I've seen before include "Book reviewer's comments may be" , "serious" , "Urgent or carping" , "Decisive - grave" , "Key" .)