Damage spirit of boundary (6)
I believe the answer is:
margin
'boundary' is the definition.
(I know that margin is a type of boundary)
'damage spirit' is the wordplay.
'damage' becomes 'mar' (to mar is to spoil or damage).
'spirit' becomes 'gin' (alcoholic spirit).
'mar'+'gin'='MARGIN'
'of' is the link.
(Other definitions for margin that I've seen before include "bank" , "Permissible difference" , "Periphery" , "Bound" , "Space at edge of page" .)