Engineer held by potentate's lawyers (5)
I believe the answer is:
tesla
'engineer' is the definition.
(I know that Tesla is a electrical engineer)
'held by potentate's lawyers' is the wordplay.
'held by' indicates the answer is hidden within the clue.
'TESLA' can be found hidden inside 'potentates lawyers'.
(Other definitions for tesla that I've seen before include "Californian company specialising in electric cars" , "Nikola ---, electricity pioneer" , "electrical unit" , "Inventive sort" , "Physics unit" .)