Dull British country (5)
I believe the answer is:
bland
'dull' is the definition.
(similar in meaning)
'british country' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in BBC).
'country' becomes 'land' (synonyms).
'b'+'land'='BLAND'
(Other definitions for bland that I've seen before include "Dull - tasteless" , "without distinctive characteristics" , "Without flavour" , "Insipid; lacklustre" , "Boringly characterless" .)