Vehicular problem presented by bonk in truck (7)

I believe the answer is:

flatbed

I'm a little stuck... Click here to teach me more about this clue!

'vehicular problem presented' is the definition.
I can't judge whether this definition defines the answer.

'by bonk in truck' is the wordplay.
'by' is a charade indicator (letters next to each other).
'bonk' becomes 'bed' (synonyms).
'in truck' becomes 'flat' (I can't explain this - if you can you should give a lot more credence to this answer).
'bed' put after 'flat' is 'FLATBED'.

Can you help me to learn more?

I've seen this clue in The Guardian.

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