Dangling extremity's long outside (7)
I believe the answer is:
pendant
'dangling' is the definition.
('pendant' can be a synonym of 'dangling')
'extremity's long outside' is the wordplay.
'extremity' becomes 'end' (end is a kind of extremity).
'long' becomes 'pant' (I've seen this before).
'outside' is an insertion indicator.
'end' inserted inside 'pant' is 'PENDANT'.
(Other definitions for pendant that I've seen before include "Ornament hanging from necklace" , "Hanging jewellery item" , "item suspended" , "Hanging light" , "earring, say" .)