Artist's empty landscapes' sad lines (1,1,5)

I believe the answer is:

l s lowry

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'artist's empty landscapes'' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.

'sad lines' is the wordplay.
I cannot quite see how this works, but
'sad' could be 'low' (I've seen this in other clues) and 'low' is found in the answer.
'lines' could be 'ry' (abbreviation for railway) and 'ry' is found within the answer.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in The Everyman puzzle in The Observer.

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