Cattle farm (5)
(Other definitions for dairy that I've seen before include "Business supplying milk etc" , "Milking parlour" , "milk supplier" , "milking cows here" , "Factory for milk products" .)
'cattle farm' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for ranch that I've seen before include "tear for a poet" , "US livestock farm" , "Agricultural business" , "Large American farm" , "North American stock farm" .)