Flexible twig and why it is brought in (5)
I believe the answer is:
withy
'flexible twig' is the definition.
'withy' can be an answer for 'twig' (withy is a kind of twig). I'm not sure about the 'flexible' bit.
'why it is brought in' is the wordplay.
'is brought in' means one lot of letters goes inside another.
'why' placed around 'it' is 'WITHY'.
'and' is the link.
Can you help me to learn more?
(Other definitions for withy that I've seen before include "Willow tree" , "The osier willow" .)