Tree house in Italy needs a lot of care inside (7)
I believe the answer is:
'tree house in italy' is the definition.
'cascara' can be an answer for 'tree'. I am not certain of the 'house in italy' bit.
'a lot of care inside' is the wordplay.
'a lot of' becomes 'casa' (I am not sure about this - if you are sure you should believe this answer much more).
'care' becomes 'car care' (car care is a kind of care).
'inside' means one lot of letters goes inside another.
'casa' going around 'car' is 'CASCARA'.
'needs' is the link.
(Other definitions for cascara that I've seen before include "purge", "Bark purgative".)