Habitual gesture (9)
I believe the answer is:
mannerism
'habitual gesture' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for mannerism that I've seen before include "Habitual gesture" , "Italian art?" , "Habitual way of behaving" , "Idiosyncrasy" , "Distinctive personal way of doing something" .)