Dance in three lines (4)
I believe the answer is:
reel
'dance' is the definition.
(I know that reel is a type of square dance)
'in three lines' is the wordplay.
'in' says the answer is hidden in the clue.
'REEL' is hidden within 'three lines'.
(Other definitions for reel that I've seen before include "Stagger about in lively dance" , "Folk dance" , "Dance - swim" , "energetic dance" , "Fishing rod attachment" .)