Ladies' blouse and dress worn by one supermarket (9)
I believe the answer is:
garibaldi
'ladies' blouse' is the definition.
(type of blouse)
'dress worn by one supermarket' is the wordplay.
'dress' becomes 'garb' (synonyms).
'worn by' is an insertion indicator (I've seen this in other clues).
'one' becomes 'I' (Roman numeral).
'supermarket' becomes 'aldi' (German supermarket also operating in the UK).
'garb' placed around 'i' is 'garib'.
'garib'+'aldi'='GARIBALDI'
'and' is the link.
(Other definitions for garibaldi that I've seen before include ""Squashed fly" biscuit?" , "Famous Italian" , "Biscuit with currants" , "Italian nationalist; biscuit" , "military commander" .)