Join in needlework (4)
I believe the answer is:
knit
I believe this clue is a double definition.
'join' is the first definition.
(I know that join is the is a more specific form of the action of knit.)
'needlework' is the second definition.
(knit is a kind of needlework)
'in' acts as a link.
(Other definitions for knit that I've seen before include "Draw (brows) together" , "mesh" , "Make something with wool and needles" , "Tighten (eyebrows) in a frown; unite" , "Make stitches?" .)