Knotted rope has secured wrist, primarily for control (5)
I believe the answer is:
power
'for control' is the definition.
(I've seen this in another clue)
'knotted rope has secured wrist primarily' is the wordplay.
'knotted' is an anagram indicator.
'has secured' means one lot of letters goes inside another.
'primarily' says to take the initial letters.
The initial letter of 'wrist' is 'w'.
'rope' with letters rearranged gives 'poer'.
'poer' going around 'w' is 'POWER'.
(Other definitions for power that I've seen before include "Strength, force" , "Ability to act or physical might" , "Force - potentiality" , "Supremacy, force" , "Large amount" .)