Isolated, practically abuse a Republican (7)
I believe the answer is:
insular
'isolated' is the definition.
(thesaurus)
'practically abuse a republican' is the wordplay.
'practically' means to remove the last letter.
'abuse' becomes 'insult' ('insult' can be a synonym of 'abuse').
'a republican' becomes 'ar' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'insult' with its last letter taken off is 'insul'.
'insul'+'ar'='INSULAR'
Can you help me to learn more?
(Other definitions for insular that I've seen before include "Lacking contact with other people" , "Inward-looking" , "Parochial" , "Lacking contact with others" , "Detached from mainstream" .)