Crossword Genius

Impractical to leave California without a justifying reason (7)

Ross

I believe the answer is:

useless

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

'impractical' is the definition.
(thesaurus)

'leave california without a justifying reason' is the wordplay.
I cannot quite see how this works, but
'without' could be 'less' (I've seen this in another clue) and 'less' is found in the answer.
The remaining letters 'use' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...

'to' acts as a link.

Can you help me to learn more?

(Other definitions for useless that I've seen before include "Futile and unavailing" , "Far from impressive" , "Is Sue less impractical?" , "Good for nothing" , "Having no beneficial function" .)

I've seen this clue in The Hindu.
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