Interweave (6)
I believe the answer is:
splice
'interweave' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for splice that I've seen before include "Join ropes together by interweaving" , "Join (ropes) by interweaving strands" , "Join rope ends together by weaving" , "Interweave strands" , "Join (rope or wedding couple)" .)