Shrub is a little dear, but useful (7)
I believe the answer is:
arbutus
'shrub' is the definition.
(I know that arbutus is a type of shrub)
'a little dear but useful' is the wordplay.
'a little' says the answer is hidden in the clue (a little bit of the clue).
'ARBUTUS' is hidden in the letters of 'dear but useful'.
'is' is the link.
(Other definitions for arbutus that I've seen before include "Plant" , "Evergreen tree or shrub with strawberry-like fruits" , "But Ursa could become a strawberry tree" , "Evergeen" , "Strawberry-tree" .)