Come back about vicious mongrel dog (5)
I believe the answer is:
recur
'come back' is the definition.
(recurring is a kind of coming back)
'vicious mongrel dog' is the wordplay.
'vicious' becomes 're' (I can't explain this - if you can you should give a lot more credence to this answer).
'mongrel dog' becomes 'cur' (I've seen this before).
're'+'cur'='RECUR'
'about' is the link.
Can you help me to learn more?
(Other definitions for recur that I've seen before include "Come round again" , "expected to return" , "Persist" , "Happen again or repetitively" , "come back to one's mind" .)