Stop enclosing area for engine driver (5)
I believe the answer is:
steam
'for engine driver' is the definition.
(a steam engine is powered by steam)
'stop enclosing area' is the wordplay.
I cannot quite see how this works, but
'area' could be 'a' (maths abbreviation) and 'a' is located in the answer.
'stop' could be 'stem' (stemming is a kind of stopping) and 'stem' is located in the remaining letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for steam that I've seen before include "Form of water" , "Momentum - boiled water" , "Vaporised water" , "Hot water vapour" , "Travel in liner" .)