Car user losing key in Thames, perhaps (5)
I believe the answer is:
river
'car' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for river that I've seen before include "Eg, Severn" , "Current" , "Slow-cooked meat dish" , "Dee, Exe or Wye, say" , "Tees, perhaps" .)