Unthinking repetition (4)
I believe the answer is:
rote
'unthinking repetition' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for rote that I've seen before include "Repetition from memory" , "By . . . . means by memory - that tore it" , "Mechanical routine" , "Habitual routine" , "By . . . . - from memory without thought" .)