Can we use an article before "one more"? For example: "Please give me a one more coffee." Thanks in advance!
In ordinary, everyday English, a native speaker would not say '*Give me a one more coffee'.
Instead, he or she would say
'Give me one more coffee'
'Give me another coffee'.
One more can be considered a determiner and usually a noun phrase utilizes only one determiner. The indefinite article a is also a determiner, so combining a with one more results in two determiners.