Catches on thin branches (5)
I believe the answer is:
twigs
This clue might be a double definition.
'catches on' is the first definition.
('twig' can be a synonym of 'catch on')
'thin branches' is the second definition.
'twigs' can be an answer for 'branches' (twigging is a kind of branching). I'm not certain of the 'thin' bit.
Can you help me to learn more?
(Other definitions for twigs that I've seen before include "Catches on" , "Small branches" , "Slender (tree) shoots" , "Slender woody shoots" , "Kindling" .)