Cereal snubbed - too much American dairy product (7)
I believe the answer is:
ricotta
'dairy product' is the definition.
(ricotta is a kind of dairy product)
'cereal snubbed too much american' is the wordplay.
'cereal' becomes 'ric' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'snubbed' means to remove the last letter (could historically mean cutting the end off).
'too much' becomes 'OTT' (short for over the top).
'american' becomes 'Am' (abbreviation in some contexts).
'ott'+'am'='ottam'
'ottam' with its final letter taken off is 'otta'.
'ric'+'otta'='RICOTTA'
Can you help me to learn more?
(Other definitions for ricotta that I've seen before include "Ital. cheese" , "cheese, Italian style" , "Italian curd cheese" , "Cheese - Riot Act (anag)" , "Italian 8 across" .)