A rocky romance fuelled by one drink (9)
I believe the answer is:
americano
'drink' is the definition.
(type of coffee drink)
'a rocky romance fuelled by one' is the wordplay.
I cannot really understand how this works, but
'a' could be 'an' and 'an' is present in the answer.
'one' could be 'me' (a setter might use 'one' to humourously mean 'me') and 'me' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for americano that I've seen before include "drink" , "Style of coffee" , "Espresso diluted with hot water" .)