Endure crossing river for beach (6)
I believe the answer is:
strand
'for beach' is the definition.
(beach can mean to become stranded on a beach)
'endure crossing river' is the wordplay.
I cannot quite understand how this works, but
'river' could be 'r' (abbreviation) and 'r' is found within the answer.
'endure' could be 'stand' (synonyms) and 'stand' is located in the leftover letters.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for strand that I've seen before include "Drive aground on shore" , "Leave in helpless position" , "Leave aground on shore" , "Beach; London road" , "Run aground, beach" .)