Aggressive dog almost hurting pointer (6)
I believe the answer is:
cursor
'pointer' is the definition.
(I know that pointer can be written as cursor)
'aggressive dog almost hurting' is the wordplay.
'aggressive dog' becomes 'cur' (cur can mean an aggressive or scruffy dog).
'almost' means to remove the last letter (most of the word but not all of it).
'hurting' becomes 'sore' (synonyms).
'sore' with its last letter taken away is 'sor'.
'cur'+'sor'='CURSOR'
(Other definitions for cursor that I've seen before include "Movable screen pointer" , "Feature of computer" , "Indicator on computer monitor" , "that may appear on computer screen" , "Moving indicator on computer screen" .)