Repeated procedure keeps them in control (6)
I believe the answer is:
remote
'control' is the definition.
(remote control)
'repeated procedure keeps them' is the wordplay.
'repeated procedure' becomes 'rote' (I have seen 'Mechanical procedure ' mean 'rote' so perhaps 'procedure' could also mean 'rote'. I am not sure about the 'repeated' bit.).
'keeps' means one lot of letters goes inside another (inserted letters are kept inside).
'them' becomes 'em' ('em is an informal way of saying 'them').
'rote' enclosing 'em' is 'REMOTE'.
'in' is the link.
Can you help me to learn more?
(Other definitions for remote that I've seen before include "At a great distance" , "Far away in time or place" , "station selector?" , "Distant, far away" , "rather aloof" .)