Cornish consumers are the tops (8)
I believe the answer is:
sweaters
'the tops' is the definition.
'cornish consumers' is the wordplay.
'cornish' becomes 'sw' (Cornwall is in the South West of England).
'consumers' becomes 'eaters' (eater is a kind of consumer).
'sw'+'eaters'='SWEATERS'
'are' acts as a link.
(Other definitions for sweaters that I've seen before include "Jerseys, pullovers" , "Knitted upper garments" , "Jumpers or pullovers - make you perspire" .)