Country rejecting centre ground's protest (6)
I believe the answer is:
outcry
'protest' is the definition.
(I've seen this before)
'country rejecting centre ground's' is the wordplay.
'rejecting centre' suggests removing the centre.
'ground' indicates an anagram ('grind' the letters into a new form).
'country' with its middle removed is 'coutry'.
'coutry' with letters rearranged gives 'OUTCRY'.
(Other definitions for outcry that I've seen before include "Great fuss" , "Public clamour" , "A storm of protest" , "Public show of anger" , "Vociferous protest" .)