Fellow accepting American with Romeo having energy: that's sweet (8)
I believe the answer is:
marzipan
'sweet' is the definition.
(I know that marzipan is a type of sweet)
'fellow accepting american with romeo having energy' is the wordplay.
I cannot quite understand how this works, but
'american' could be 'a' (common abbreviation - e.g. in organisation names) and 'a' is found within the answer.
'romeo' could be 'r' (phonetic alphabet: alpha, bravo, charlie etc.) and 'r' is found in the answer.
'energy' could be 'zip' (I've seen this before) and 'zip' is located in the answer.
'fellow' could be 'man' (fellow can mean a man) and 'man' is located in the remaining letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'that's' is the link.
Can you help me to learn more?
(Other definitions for marzipan that I've seen before include "Kind of icing, nice on cakes" , "that's sweet" , "Marchpane" , "coat often iced over?" , "Cake topping" .)