Nervous about Tesla's gearbox position breaking transmission (7)
I believe the answer is:
neutral
'transmission' is the definition.
(thesaurus)
'nervous about tesla's' is the wordplay.
'nervous' becomes 'neural' (synonyms).
'about' indicates putting letters inside.
'tesla' becomes 'T' (scientific unit).
'neural' enclosing 't' is 'NEUTRAL'.
'gearbox position breaking' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for neutral that I've seen before include "'Neither good nor evil, nor right nor wrong (7)'" , "Not allied to either side" , "Not supporting or favouring either side" , "Supporting neither side" , "having no potential" .)