Unthinkingly repeat standard nonsense (6)
I believe the answer is:
parrot
'unthinkingly repeat' is the definition.
'parrot' can be an answer for 'repeat' (parroting is a kind of repeating). I am not certain of the 'unthinkingly' bit.
'standard nonsense' is the wordplay.
'standard' becomes 'par' (standard of play in golf).
'nonsense' becomes 'rot' (rot can mean nonsense or rubbish).
'par'+'rot'='PARROT'
Can you help me to learn more?
(Other definitions for parrot that I've seen before include "Repeat by rote" , "Imitative bird" , "Brightly coloured tropical bird" , "Repeat automatically" , "18's [BIRD]" .)