Stop crossing river and fold (6)
I believe the answer is:
crease
'fold' is the definition.
(I know that fold can be written as crease)
'stop crossing river' is the wordplay.
I cannot quite see how this works, but
'river' could be 'ea' (I've seen this in other clues) and 'ea' is found within the answer.
This explanation may well be incorrect...
'and' is the link.
Can you help me to learn more?
(Other definitions for crease that I've seen before include "Folded line" , "Fold; batsman's position" , "Dagger rarely" , "ruck" , "Mark made by fold" .)