The legitimate position Edison could have been in (6)
I believe the answer is:
onside
'the legitimate' is the definition.
(I've seen this before)
'position edison could have been in' is the wordplay.
'edison' anagrams to 'ONSIDE'.
However, I'm not sure how this is indicated.
Can you help me to learn more?
(Other definitions for onside that I've seen before include "Legally positioned in game" , "Working towards the same goal" , "in a permitted position in sport" , "Cricket's leg" , "In agreement (colloq.)" .)