Suck-up (5)
I believe the answer is:
toady
'suck-up' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for toady that I've seen before include "Flatterer or sycophant" , "Yes-man" , "fawn" , "Person who flatters and behaves obsequiously to another" , "Obsequious type" .)