Drink suppliers were realigned, investing in cheese products (9)
I believe the answer is:
breweries
'drink suppliers' is the definition.
(breweries supply beer which is a drink)
'were realigned investing in cheese products' is the wordplay.
'realigned' indicates anagramming the letters.
'investing in' indicates putting letters inside.
'cheese products' becomes 'bries' (Brie is an example).
'were' is an anagram of 'ewer'.
'ewer' inserted into 'bries' is 'BREWERIES'.
(Other definitions for breweries that I've seen before include "Companies that produce beer" , "Places in which beer is made" , "Fermenting plants for alcoholic beverages" .)