Shanty cop - terrible yes-man (9)
I believe the answer is:
sycophant
'yes-man' is the definition.
(I've seen this before)
'shanty cop terrible' is the wordplay.
'terrible' indicates an anagram.
'shanty'+'cop'='shantycop'
'shantycop' with letters rearranged gives 'SYCOPHANT'.
(Other definitions for sycophant that I've seen before include "Uriah Heep, say" , "receiving ultimate in flattery from one such?" , "yes-man" , "Servile flatterer" , "Crawler, toady" .)