Repeat without understanding (6)
I believe the answer is:
parrot
'repeat without understanding' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for parrot that I've seen before include "Bird (that repeats)" , "Vividly coloured bird" , "Raucous bird" , "Spout" , "Copycat who does not understand words or acts imitated" .)