Somehow let tree heat material (11)
I believe the answer is:
leatherette
'material' is the definition.
(Leatherette is an example)
'somehow let tree heat' is the wordplay.
'somehow' is an anagram indicator.
'let'+'tree'+'heat'='lettreeheat'
'lettreeheat' with letters rearranged gives 'LEATHERETTE'.
(Other definitions for leatherette that I've seen before include "Imitation hide" , "Imitation material" .)