Supply extremely durable uniform (8)
I believe the answer is:
delivery
'supply' is the definition.
(thesaurus)
'extremely durable uniform' is the wordplay.
'extremely' suggests removing the centre (letters on the extremes of the word are used).
'uniform' becomes 'livery' (livery is a type of formal uniform).
'durable' with its middle taken out is 'de'.
'de'+'livery'='DELIVERY'
(Other definitions for delivery that I've seen before include "Chinaman, perhaps" , "Address" , "Throw of a cricket ball" , "Handing over - manner of speaking" , "A handing over of goods" .)