Tree house entered with caution for the most part (7)
I believe the answer is:
cascara
'tree' is the definition.
'house entered with caution for the most part' is the wordplay.
'house' becomes 'casa' (Spanish word for 'house' also used in English).
'entered with' indicates putting letters inside.
'caution' becomes 'card' (I've seen this before).
'for the most part' means to remove the last letter.
'card' with its final letter taken away is 'car'.
'casa' going around 'car' is 'CASCARA'.
(Other definitions for cascara that I've seen before include "Bark purgative" , "purge" .)