Piece of plaid tied in a knot or intertwined (7)
I believe the answer is:
plaited
'intertwined' is the definition.
(thesaurus)
'piece of plaid tied in a knot' is the wordplay.
'piece of plaid' becomes 'pla' (I can't explain this - if you can you should give a lot more credence to this answer).
'in a knot' indicates an anagram.
'tied' anagrammed gives 'ited'.
'pla'+'ited'='PLAITED'
'or' acts as a link.
Can you help me to learn more?
(Other definitions for plaited that I've seen before include "queue, perhaps" , "Braided or interlaced" , "Of hair, woven into rope-like length" , "(Of hair) braided" , "In interlaced strands" .)