Coming by river is a daring enterprise (9)
I believe the answer is:
'daring enterprise' is the definition.
'adventure' can be an answer for 'enterprise' (I've seen this before). I am not sure about the 'daring' bit.
'coming by river' is the wordplay.
'coming' becomes 'advent' (advent is the arrival or coming of something).
'by' says to put letters next to each other.
'river' becomes 'ure' (river in Yorkshire).
'is a' acts as a link.
Can you help me to learn more?
(Other definitions for adventure that I've seen before include "that may be exciting" , "Exciting or daring experience" , "speculation" , "Risk" , "Hazardous operation" .)