Huge nation lacking a feature (4)
I believe the answer is:
chin
'a feature' is the definition.
(facial feature)
'huge nation lacking' is the wordplay.
'huge' becomes 'chi' (I can't justify this - if you can you should give a lot more credence to this answer).
'nation' becomes 'NZ' (abbreviation for New Zealand).
'lacking' means to remove the last letter (the word is incomplete or lacking).
'nz' with its last letter taken away is 'n'.
'chi'+'n'='CHIN'
Can you help me to learn more?
(Other definitions for chin that I've seen before include "Could be a double feature" , "Point of the jaw" , "Part of the face (on which one may have to take it?)" , "Punch to the face" , "Possible double feature?" .)