Companion at home finally cut variable cotton fabric (6)
I believe the answer is:
chintz
'cotton fabric' is the definition.
(I've seen this before)
'companion at home finally cut variable' is the wordplay.
'companion' becomes 'ch' (Companion of Honour).
'at home' becomes 'in' ('I'm in' can mean 'I'm at home').
'finally' says to take the final letters.
'variable' becomes 'z' (algebra).
The final letter of 'cut' is 't'.
'ch'+'in'+'t'+'z'='CHINTZ'
(Other definitions for chintz that I've seen before include "Glazed cotton cloth with printed pattern" , "Glazed cotton print" , "Cotton cloth with printed patterns used for furnishings" , "Shiny cotton fabric used for furnishings" , "Printed cotton fabric for curtains or upholstery" .)