Motors seen erroneously to contain spirit (7)
I believe the answer is:
engines
'motors' is the definition.
(I know this)
'seen erroneously to contain spirit' is the wordplay.
'erroneously' is an anagram indicator.
'to contain' means one lot of letters goes inside another.
'spirit' becomes 'gin' (alcoholic spirit).
'seen' anagrammed gives 'enes'.
'enes' enclosing 'gin' is 'ENGINES'.
(Other definitions for engines that I've seen before include "Powerful machines" , "Machines that convert power into motion" , "Motors" , "Locomotives" .)