Traveller on street finds tissue (6)

I believe the answer is:

stroma

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'tissue' is the definition.
(stroma is a kind of tissue)

'traveller on street finds' is the wordplay.
'traveller' becomes 'rom' (individual belonging to the Romani people).
'on' means one lot of letters go next to another.
'street' becomes 'st'.
'finds' becomes 'a' (I can't explain this - if you can you should give a lot more credence to this answer).
'rom' put after 'st' is 'strom'.
'strom'+'a'='STROMA'

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I've seen this clue in The Independent.

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