Castle hit -- destroyed for sport (9)
I believe the answer is:
athletics
'sport' is the definition.
(synonyms)
'castle hit destroyed' is the wordplay.
'destroyed' indicates anagramming the letters.
'castle'+'hit'='castlehit'
'castlehit' with letters rearranged gives 'ATHLETICS'.
'for' is the link.
(Other definitions for athletics that I've seen before include "Lithe acts performed in physical sports" , "Running and jumping" , "Oldham and Charlton?" , "on the track, perhaps" , "Track and field sports" .)