Country is dull, but not initially (4)
I believe the answer is:
land
'country' is the definition.
(synonyms)
'dull but not initially' is the wordplay.
'dull' becomes 'bland' (similar in meaning).
'but not initially' means to remove the first letter.
'bland' with its initial letter taken off is 'LAND'.
'is' is the link.
(Other definitions for land that I've seen before include "people" , "(Of aircraft) alight" , "Area of ground" , "Part of Germany" , "Property" .)