From head to tail, unusually fine (7)
I believe the answer is:
capital
'fine' is the definition.
(thesaurus)
'from head to tail unusually' is the wordplay.
I cannot really understand how this works, but
'head' could be 'cap' (both can mean the top of something) and 'cap' is found within the answer.
an anagram of 'tail' is 'ital' which is present in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for capital that I've seen before include "Upper-case letter" , "Seed money" , "Most important city" , "Means" , "Wealth; main city" .)