Crossword Genius

Industry vehicle (9)

Ross

I believe the answer is:

diligence

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

This might be a double definition.

'industry' is the first definition.
(synonyms)

'vehicle' is the second definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.

Can you help me to learn more?

(Other definitions for diligence that I've seen before include "Careful and persistent work or effort" , "needing proper care and attention" , "Old stagecoach" , "hard effort" , "Thoroughgoing application" .)

I've seen this clue in the Sydney Morning Herald.
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