Cereal with posher nuts for local business (6,4)
I believe the answer is:
corner shop
'local business' is the definition.
'cereal with posher nuts' is the wordplay.
'cereal' becomes 'corn' (corn is a kind of cereal**).
'with' is a charade indicator (letters next to each other).
'nuts' is an anagram indicator (nuts can mean crazy).
'posher' with letters rearranged gives 'ershop'.
'corn'+'ershop'='CORNER SHOP'
'for' is the link.
(Other definitions for corner shop that I've seen before include "Local outlet" , "Small retail outlet" , "Retail establishment on the angle of two streets?" , "Small local retailer" .)