Labour with energy in thin cotton (5)

I believe the answer is:

toile

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'thin cotton' is the definition.
The definition suggests a singular noun which matches the answer.

'labour with energy' is the wordplay.
'labour' becomes 'toil' (synonyms).
'with' says to put letters next to each other.
'energy' becomes 'e' (physics symbol as in E=mc2).
'toil'+'e'='TOILE'

'in' acts as a link.

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(Other definitions for toile that I've seen before include "Worked hard" , "dress material" , "6 [LINEN]" , "cheap prototype" , "Fabric" .)

I've seen this clue in The Times.

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