Stranded dinghy had broken down crossing river (4,3,3)
I believe the answer is:
high and dry
'stranded' is the definition.
(I've seen this before)
'dinghy had broken down crossing river' is the wordplay.
'broken down' is an anagram indicator.
'crossing' is an insertion indicator.
'river' becomes 'r'.
'dinghy'+'had'='dinghyhad'
'dinghyhad' anagrammed gives 'highanddy'.
'highanddy' enclosing 'r' is 'HIGH-AND-DRY'.
(Other definitions for high and dry that I've seen before include "like Noah on Ararat?" , "Stranded, helpless" , "Without resources" .)