A cast that's tree-like (4)
I believe the answer is:
ashy
'tree-like' is the definition.
I can't judge whether this definition defines the answer.
'a cast' is the wordplay.
'cast' becomes 'shy' (I've seen this before).
'a'+'shy'='ASHY'
'that's' is the link.
Can you help me to learn more?
(Other definitions for ashy that I've seen before include "Like, eg, volcanic dust" , "evidence of recent fire" , "resembling cinder track?" , "Like burnt remains" , "Like burnt residue" .)