He grovels now as duke is coming down (5)
I believe the answer is:
toady
'he grovels' is the definition.
'now as duke is coming down' is the wordplay.
I cannot quite see how this works, but
'now' could be 'ad' (I've seen this in other clues) and 'ad' is found within the answer.
The remaining letters 'toy' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
(Other definitions for toady that I've seen before include "crawler" , "fawn" , "Person who flatters and behaves obsequiously to another" , "Creep" , "Curry favour" .)