One crashed in mid-March? (3)
I believe the answer is:
car
'mid-march?' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'one crashed in' is the wordplay.
'one' becomes 'a' (a thing is one thing).
'crashed' becomes 'cr' (I am not sure about this - if you are sure you should believe this answer much more).
'in' is an insertion indicator.
'a' put inside 'cr' is 'CAR'.
Can you help me to learn more?
(Other definitions for car that I've seen before include "Wheeled vehicle" , "Personal vehicle" , "Vehicle carrying vehicles" , "Hatchback, say?" , "Motor vehicle" .)