The writer served up crackers and cheese (8)
I believe the answer is:
emmental
'cheese' is the definition.
(I know that Emmental is a type of Swiss cheese)
'the writer served up crackers' is the wordplay.
'the writer' becomes 'me' (the person who wrote the clues).
'served up' shows that the letters should be reversed in order (in a down clue, going upwards).
'crackers' becomes 'mental' (I can't justify this - if you can you should give a lot more credence to this answer).
'me' written backwards gives 'em'.
'em'+'mental'='EMMENTAL'
'and' acts as a link.
Can you help me to learn more?
(Other definitions for emmental that I've seen before include "Cheese for the metal men" , "Swiss food" , "Something served on board" , "Gruyere-like cheese" , "Swiss cheese with large holes" .)