Repeating tie knot, I have to follow traitor (9)
I believe the answer is:
iterative
'repeating' is the definition.
(I've seen this in another clue)
'tie knot i have to follow traitor' is the wordplay.
'knot' indicates anagramming the letters (I've seen 'knotted' mean this).
'i have' becomes 'I've' (contraction of 'I have').
'to follow' is a charade indicator (letters next to each other).
'traitor' becomes 'rat' (rat can mean a traitor).
'tie' with letters rearranged gives 'ite'.
'ive' put after 'rat' is 'rative'.
'ite'+'rative'='ITERATIVE'
(Other definitions for iterative that I've seen before include "repeated" , "bears repeating" , "Involving repetition" , "Relating to repetition" .)