Usual standard, rubbish mimic (6)
I believe the answer is:
parrot
'mimic' is the definition.
(I've seen this in another clue)
'usual standard rubbish' is the wordplay.
'usual standard' becomes 'par' (golf).
'rubbish' becomes 'rot' (both can mean nonsense).
'par'+'rot'='PARROT'
(Other definitions for parrot that I've seen before include "Eg, macaw" , "Repeater" , "Lory" , "Raucous bird" , "Repeat without understanding" .)