Draws one into the set-up (4)
I believe the answer is:
ties
'draws' is the definition.
('tie' can be a synonym of 'draw')
'one into the set-up' is the wordplay.
'one' becomes 'i' (Roman numeral).
'into' indicates putting letters inside.
'up' says the letters should be written backwards (in down clue: letters go upwards).
'i' going into 'set' is 'seit'.
'seit' back-to-front is 'TIES'.
(Other definitions for ties that I've seen before include "obligations" , "Links" , "Attaches, knots" , "Fastens with a knot" , "allegiances" .)