Settled opinion piece about Tesla (5)

I believe the answer is:
opted
'settled' is the definition.
Both the definition and answer are past participle verbs.
Perhaps there's an association between them I don't understand?
'opinion piece about tesla' is the wordplay.
'opinion piece' becomes 'op-ed' (part of a newspaper offering opinion pieces).
'about' means one lot of letters goes inside another.
'tesla' becomes 'T' (scientific unit).
'oped' enclosing 't' is 'OPTED'.
Can you help me to learn more?
(Other definitions for opted that I've seen before include "Depot (anag.)" , "Chosen - elected" , "Made choice, selected" , "Chose from depot" , "Decided as in 10 Across" .)
