Tree Truro wants to protect (5)
I believe the answer is:
rowan
'tree' is the definition.
(rowan is a kind of tree)
'truro wants to protect' is the wordplay.
'to protect' indicates the answer is hidden within the clue (the answer is protected by the clue).
'ROWAN' is hidden within 'truro wants'.
(Other definitions for rowan that I've seen before include "Red-berried tree" , "source of berries" , "Mr Atkinson, actor" , "Canterbury" , "Tree bearing bright red berries" .)