Giant bird on banks of Amazon (5)
I believe the answer is:
titan
'giant' is the definition.
(titans are giant mythological creatures)
'bird on banks of amazon' is the wordplay.
'bird' becomes 'tit' (tit is a kind of bird).
'on' says to put letters next to each other.
'banks of' suggests removing the centre (the banks are the sides of the word).
'amazon' with its centre removed is 'an'.
'tit'+'an'='TITAN'
(Other definitions for titan that I've seen before include "One of the mythological Greek giants who ruled the world" , "enormous thing" , "A giant; Saturn moon" , "Hyperion, for example" , "Very strong or important person" .)