Die in water, having fallen crossing river (5)
I believe the answer is:
drown
'die in water' is the definition.
(I've seen this before)
'fallen crossing river' is the wordplay.
'fallen' becomes 'down' (I can't explain this - if you can you should believe this answer much more).
'crossing' means one lot of letters goes inside another.
'river' becomes 'r' (abbreviation for river).
'down' placed around 'r' is 'DROWN'.
'having' is the link.
Can you help me to learn more?
(Other definitions for drown that I've seen before include "Suffocate in liquid" , "Die from submersion in liquid" , "Submerge, maybe fatally" , "Die in sea" , "Die in water" .)