Incarnation of backsliding renegade, a vice-admiral (6)
I believe the answer is:
avatar
'incarnation' is the definition.
('avatar' can be a synonym of 'incarnation')
'backsliding renegade a vice-admiral' is the wordplay.
'backsliding' is a reversal indicator.
'renegade' becomes 'rat' (I've seen this before).
'vice admiral' becomes 'va' (this might be a standard abbreviation I've not previously seen).
'rat'+'a'+'va'='ratava'
'ratava' written backwards gives 'AVATAR'.
'of' is the link.
Can you help me to learn more?
(Other definitions for avatar that I've seen before include "New personification of a familiar idea" , "Online image" , "Hindu manifestation of deity in human form" , "Divine appearance" , "Person seen as embodying a particular ideal" .)