Bend over stream after large amount of drink, then come to grief spectacularly (5,3,4)

'come to grief spectacularly' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.

'bend over stream after large amount of drink' is the wordplay.
'bend' becomes 'arc' (arc can mean to curve or bend).
'over' says the letters should be written in reverse.
'stream' becomes 'burn' (a burn is a small stream).
'after' says to put letters next to each other.
'large amount of drink' becomes 'shand' (I am not sure about this - if you are sure you should believe this answer much more).
'arc' reversed gives 'cra'.
'burn' put after 'shand' is 'shandburn'.
'cra'+'shandburn'='CRASH AND BURN'

'then' is the link.

Can you help me to learn more?