Tree centre of snowy mountain chain (6)
I believe the answer is:
orange
'tree' is the definition.
(orange is a kind of tree)
'centre of snowy mountain chain' is the wordplay.
'centre of' means to look at the middle letters.
'mountain chain' becomes 'range' (synonyms).
The centre of 'snowy' is 'o'.
'o'+'range'='ORANGE'
(Other definitions for orange that I've seen before include "stocking filler" , "One's pipped" , "soft drink?" , "Fruit; pigment" , "divided internally, naturally" .)