About to get Grauniad's ultimate compiler a dog (3,6)
I believe the answer is:
red setter
'a dog' is the definition.
(red setter is a kind of dog)
'about to get grauniad's ultimate compiler' is the wordplay.
'about' becomes 're' (regarding**).
'to get' is a charade indicator (letters next to each other).
'ultimate' suggests the final letters.
'compiler' becomes 'setter' (both can mean a writer of crosswords).
The last letter of 'grauniad' is 'd'.
're'+'d'+'setter'='RED SETTER'
(Other definitions for red setter that I've seen before include "description of evening sun?" , "Barker" , "Breed of dog" , "Gun dog" , "Pet" .)