A river bird and parent create Nile blockage (5,3)
I believe the answer is:
aswan dam
'nile blockage' is the definition.
(dam in the River Nile)
'a river bird and parent' is the wordplay.
'river bird' becomes 'swan' (bird which may live by a river).
'and' is a charade indicator (letters next to each other).
'parent' becomes 'dam' (term for the female parent of an animal).
'a'+'swan'+'dam'='ASWAN DAM'
'create' is the link.
(Other definitions for aswan dam that I've seen before include "Egyptian water barrier" , "Huge structure in Africa" , "Egypt's lake district" , "massive barrier" , "Nile construction of 1902" .)