Come again about the dog (5)
I believe the answer is:
recur
'come again' is the definition.
(I've seen this in another clue)
'about the dog' is the wordplay.
'about' becomes 're' (regarding).
'the dog' becomes 'cur' (a cur is an aggressive or scruffy dog).
're'+'cur'='RECUR'
(Other definitions for recur that I've seen before include "Return to mind" , "Be repeated" , "come back to one's mind" , "Come round again" , "Repeat" .)