Curbs and tricks public transport (10)

I believe the answer is:

constrains

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

'curbs' is the definition.
The answer and definition can be both related to change as well as being verbs in their -s form.
Maybe you can see a link between them that I can't see?

'tricks public transport' is the wordplay.
'tricks' becomes 'cons' (trick can mean to scam or con).
'public transport' becomes 'trains'.
'cons'+'trains'='CONSTRAINS'

'and' is the link.

Can you help me to learn more?

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

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