Go ashore with rating for historic event (8)
I believe the answer is:
landmark
'historic event' is the definition.
(I've seen this before)
'go ashore with rating' is the wordplay.
'go ashore' becomes 'land' (I've seen this in another clue).
'with' means one lot of letters go next to another.
'rating' becomes 'mark' (mark is a kind of rating).
'land'+'mark'='LANDMARK'
'for' acts as a link.
(Other definitions for landmark that I've seen before include "cairn, possibly" , "Significant feature or event" , "Notable geographical feature" , "Easily identifiable monument, for example" , "Damn lark (anag.)" .)