Identify American in river (5)
I believe the answer is:
tagus
'river' is the definition.
(Tagus is an example)
'identify american' is the wordplay.
'identify' becomes 'tag' (I've seen this in other clues).
'american' becomes 'US' (abbreviation for United States).
'tag'+'us'='TAGUS'
'in' acts as a link.
(Other definitions for tagus that I've seen before include "Portuguese river flowing to sea near Lisbon" , "Current" , "European river" , "river abroad" , "Longest river of Iberian peninsula" .)