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