How the car crossed the river? (6)
I believe the answer is:
forded
'crossed the river?' is the definition.
'forded' can be an answer for 'crossed' (fording is a kind of crossing). I'm unsure of the 'the river?' bit.
'how the car' is the wordplay.
I cannot quite understand how this works, but
'car' could be 'ford' (Ford is a make of car) and 'ford' is found in the answer.
The remaining letters 'ed' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for forded that I've seen before include "Crossed river on foot at shallow place" , "Crossed river at shallow point" .)