Is the old currency English in that country? (6)
I believe the answer is:
france
'that country?' is the definition.
(France is an example)
'is the old currency english' is the wordplay.
I cannot really understand how this works, but
'currency' could be 'franc' (old French currency) and 'franc' is found in the answer.
'english' could be 'e' (abbreviation as in OED) and 'e' is found within the answer.
No letters remain.
This explanation may well be incorrect...
'in' is the link.
Can you help me to learn more?
(Other definitions for france that I've seen before include "Anatole ---, Fr. novelist" , "Nice country!" , "One of the six original members of the European Economic Community" , "Paris its capital" , "Sarkozy's republic" .)