Capital's aberrancy mostly represented (8)
I believe the answer is:
canberra
'capital's' is the definition.
(capital of Australia)
'aberrancy mostly represented' is the wordplay.
'mostly' means to remove the last letter (most but not all of the word).
'represented' indicates an anagram.
'aberrancy' with its final letter removed is 'aberranc'.
'aberranc' anagrammed gives 'CANBERRA'.
(Other definitions for canberra that I've seen before include "Strange crab near Australia" , "Australian capital - old ship" , "Capital - bomber - liner" , "Nab racer, oddly, in Australia" , "Australian city" .)