Hole in branch by top of acacia produces scent (5)
I believe the answer is:
aroma
'scent' is the definition.
('aroma' can be a synonym of 'scent')
'hole in branch by top of acacia' is the wordplay.
'hole' becomes 'o'.
'in' is an insertion indicator.
'branch' becomes 'arm' ('arm' can be a synonym of 'branch'**).
'by' is a charade indicator (letters next to each other).
'top of' suggests taking the first letters.
The initial letter of 'acacia' is 'a'.
'o' placed into 'arm' is 'arom'.
'arom'+'a'='AROMA'
'produces' acts as a link.
(Other definitions for aroma that I've seen before include "Stink" , "Redolence" , "Spicy fragrance" , "Fragrance of spices" , "Scent - smell" .)