Setter's upward stroke blocks shot — pity! (8)
I believe the answer is:
sympathy
'pity' is the definition.
(I know that pity can be written as sympathy)
'setter's upward stroke blocks shot' is the wordplay.
'setter's upward' becomes 'ym' (I can't justify this - if you can you should believe this answer much more).
'stroke' becomes 'pat' (pat can mean to stroke or touch).
'blocks' means one lot of letters goes inside another (the inside letters form a 'blockage').
'shot' becomes 'shy' (both can mean an act of throwing something).
'ym'+'pat'='ympat'
'ympat' going inside 'shy' is 'SYMPATHY'.
(Other definitions for sympathy that I've seen before include "Fellow feeling, understanding" , "Condolences; understanding" , "Accord" , "Feeling of pity and understanding towards another's difficulty" , "often offered with tea" .)