Stone cast in attack (5)
I believe the answer is:
onset
'attack' is the definition.
(archaic term for a military attack)
'stone cast' is the wordplay.
'cast' indicates anagramming the letters (letters are dispersed or cast around).
'stone' anagrammed gives 'ONSET'.
'in' is the link.
(Other definitions for onset that I've seen before include "Appearance of" , "Start, beginning" , "Inception" , "First signs" , "Outbreak" .)