Starts to prune around large mulberry tree (4)
I believe the answer is:
palm
'tree' is the definition.
(palm is a kind of tree)
'starts to prune around large mulberry' is the wordplay.
'starts to' suggests taking the first letters.
The first letters of 'prune around large mulberry' is 'PALM'.
(Other definitions for palm that I've seen before include "Inner surface of the hand" , "that's inspected by a fortune-teller" , "Sign of victory" , ""trophy"" , "prize" .)