Perfect floor covering in use (10)
I believe the answer is:
consummate
'perfect' is the definition.
(synonyms)
'floor covering in use' is the wordplay.
'floor covering' becomes 'mat' (a mat is a floor covering).
'in' means one lot of letters goes inside another.
'use' becomes 'consume' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'mat' placed into 'consume' is 'CONSUMMATE'.
Can you help me to learn more?
(Other definitions for consummate that I've seen before include "total" , "Supreme, perfect; make (a marriage) complete" , "Showing great skill and flair" .)