Does an engine use none of it for half a mile? (3)
I believe the answer is:
oil
'does an engine use none' is the definition.
I can't judge whether this defines the answer.
'of it for half a mile?' is the wordplay.
'of' becomes 'o''.
'it' becomes 'l' (I am not sure about this - if you are sure you should believe this answer much more).
'for' means one lot of letters go next to another (I've seen this in other clues).
'half a' means to take half the letters.
'mile?' becomes 'mi' ('mi' can be a synonym of 'mile').
'mi' halved is 'i'.
'l' after 'i' is 'il'.
'o'+'il'='OIL'
Can you help me to learn more?
(Other definitions for oil that I've seen before include "Black gold" , "Grease" , "eg Olive" , "Viscous substance as lubricant" , "Valuable viscous liquid" .)