Part of a boa (7)
I believe the answer is:
feather
'part of a boa' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for feather that I've seen before include "dance step" , "Rotate (propeller) blades (to reduce thrust)" , "Part of covering of bird" , "thing of little importance" , "English plume (de ma tante?)" .)