Repeat thoughtlessly, or possibly in part (6)
I believe the answer is:
parrot
'repeat thoughtlessly' is the definition.
'parrot' can be an answer for 'repeat' (parroting is a kind of repeating). I am not certain of the 'thoughtlessly' bit.
'or possibly in part' is the wordplay.
'possibly' indicates anagramming the letters.
'in' is an insertion indicator.
'or' is an anagram of 'ro'.
'ro' put inside 'part' is 'PARROT'.
Can you help me to learn more?
(Other definitions for parrot that I've seen before include "One repeating" , "Eg, macaw" , "Tropical bird, may talk" , "Mimic like exotic bird" , "Bright tropical bird" .)