Cut back part of bush or tendril (7)
I believe the answer is:
shorten
'cut back' is the definition.
(shortening is a kind of cutting back)
'part of bush or tendril' is the wordplay.
'part of' indicates a hidden word.
'SHORTEN' is hidden within 'bush or tendril'.
(Other definitions for shorten that I've seen before include "Make less long" , "Truncate" , "Cut back" , "Put extra fat" , "contract" .)