Reel composed of endless curtseying (6)
I believe the answer is:
Here is my best explanation:
'reel' is the definition.
('bobbin' can be a synonym of 'reel')
'endless curtseying' is the wordplay.
'endless' means to remove the last letter.
'curtseying' becomes 'bobbing'.
'bobbing' with its last letter taken away is 'BOBBIN'.
'composed of' is the link.
(Other definitions for bobbin that I've seen before include "Spool for winding yarn", "Shuttle", "Small spool holding thread in machine", "Cotton reel", "It carries wound yarn", "Cylinder for winding thread", "Reel, spool", "Spindle for holding thread", "A spool for winding yarn" and "Reel for yarn".)