Bend at a barre (4)
I believe the answer is:
plie
'bend at a barre' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for plie that I've seen before include "8 [BALLET] term" , "Knees-bend ballet posture" , "Ballet movement bending knees while upright" , "Dance move" , "Classic ballet posture" .)