Edison worked in a lawful position (6)
I believe the answer is:
onside
'in a lawful position' is the definition.
I can't tell whether this definition defines the answer.
'edison worked' is the wordplay.
'worked' indicates an anagram.
'edison' is an anagram of 'ONSIDE'.
Can you help me to learn more?
(Other definitions for onside that I've seen before include "Cricket's leg" , "Legally positioned on field" , "not breaking rules" , "legitimate" , "is in state to continue playing" .)