In old Portuguese colony, Brook a wild animal (7)
I believe the answer is:
gorilla
'wild animal' is the definition.
'in old portuguese colony brook a' is the wordplay.
'in old portuguese colony' becomes 'go' (I can't justify this - if you can you should give a lot more credence to this answer).
'brook' becomes 'rill' (I've seen this in another clue).
'go'+'rill'+'a'='GORILLA'
Can you help me to learn more?
(Other definitions for gorilla that I've seen before include "African great ape" , "The biggest ape" , "thug" , "Large chest-beating ape" , "A large powerful African ape" .)