Nation flourishes if justice is at the fore (4)
I believe the answer is:
fiji
'nation' is the definition.
(Fiji is an example)
'flourishes if justice is at the fore' is the wordplay.
'flourishes' indicates an anagram (I've seen 'flourishing' mean this (letters grow or flourish differently)).
'justice' becomes 'j'.
'is at the fore' becomes 'i' (I am not sure about this - if you are sure you should believe this answer much more).
'if' with letters rearranged gives 'fi'.
'fi'+'j'+'i'='FIJI'
Can you help me to learn more?
(Other definitions for fiji that I've seen before include "Pacific member of the British Commonwealth" , "South Pacific republic, capital Suva" , "South Pacific country of some 840 islands" , "Pacific island member of the Commonwealth, capital Suva" , "Country of many islands" .)