Something soft to walk on is one's only luxury (4,7)

I believe the answer is:

sole comfort

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'something soft to walk' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'on is one's only luxury' is the wordplay.
'on' says to put letters next to each other.
'is one' becomes 'sole' (synonyms).
'only luxury' becomes 'comfort' (I can't justify this - if you can you should believe this answer much more).
'sole' put next to 'comfort' is 'SOLE COMFORT'.

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I've seen this clue in the Evening Standard.

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