Crossword Genius

On which to drive a generous distance? (7)

Ross

I believe the answer is:

freeway

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

'on which to drive a' is the definition.
I can't judge whether this defines the answer.

'generous distance?' is the wordplay.
'generous' becomes 'free' (I've seen this before).
'distance?' becomes 'way' (way is a kind of distance).
'free'+'way'='FREEWAY'

Can you help me to learn more?

(Other definitions for freeway that I've seen before include "No tolls on this major road!" , "road in US" , "Motorway on which stopping or parking is forbidden" , "Road without tolls" , "American road" .)

I've seen this clue in the Evening Standard.
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