Don, for example - lead-free motorist (5)
I believe the answer is:
river
'don for example' is the definition.
(I know that Don is a river)
'lead-free motorist' is the wordplay.
'lead-free' means to remove the first letter (the letter which leads the word is removed).
'motorist' becomes 'driver' (I've seen this in another clue).
'driver' with its first letter taken off is 'RIVER'.
(Other definitions for river that I've seen before include "Dee, Exe or Wye, say" , "Moon - - (song)" , "Natural flow of water" , "eg Aire" , "One splits" .)