Perhaps a tree after surgery needs work (7)
I believe the answer is:
operate
'work' is the definition.
(I know that work can be written as operate)
'perhaps a tree after surgery' is the wordplay.
'perhaps' is an anagram indicator.
'after' says to put letters next to each other.
'surgery' becomes 'op' (short for operation).
'a'+'tree'='atree'
'atree' anagrammed gives 'erate'.
'erate' after 'op' is 'OPERATE'.
'needs' is the link.
(Other definitions for operate that I've seen before include "(Of machine) function" , "Work - perform surgery" , "Conduct business in a theatre" , "Work, run" , "Make function" .)