Daring passage oddly stormier on river (11)
I believe the answer is:
venturesome
'daring passage' is the definition.
'venturesome' can be an answer for 'daring' (I've seen this in another clue). I am not sure about the 'passage' bit.
'oddly stormier on river' is the wordplay.
'oddly' means one should take alternating letters (letters in odd-numbered positions).
'on' is a charade indicator (letters next to each other).
'river' becomes 'venture' (I can't explain this - if you can you should believe this answer much more).
The alternating letters of 'stormier' are 'some'.
'some' put after 'venture' is 'VENTURESOME'.
Can you help me to learn more?
(Other definitions for venturesome that I've seen before include "Bold" , "Prepared to take risks" , "Willing to take risks" .)