Account about one pub that's served up American coffee (7)
I believe the answer is:
arabica
'coffee' is the definition.
(type of coffee plant)
'account about one pub that's served up american' is the wordplay.
'account' becomes 'cia' (I can't justify this - if you can you should give a lot more credence to this answer).
'about' is an insertion indicator.
'one pub' becomes 'bar' (both are drinking establishments).
'that's served up' is a reversal indicator (in a down clue up is reversing the order).
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'cia' enclosing 'bar' is 'cibara'.
'cibara' reversed gives 'arabic'.
'arabic'+'a'='ARABICA'
Can you help me to learn more?
(Other definitions for arabica that I've seen before include "Shrubby tree of tropical Africa cultivated for coffee" , "Variety of coffee beans" , "sort of bean" , "Variety of coffee bean" , "Type of coffee bean" .)