Carnival city - as we see it - is wild (7)
I believe the answer is:
riotous
'it is wild' is the definition.
(I've seen this before)
'carnival city as we' is the wordplay.
'carnival city' becomes 'Rio' (Rio de Janeiro is famous for its carnival).
'as' becomes 'to' (I can't justify this - if you can you should give a lot more credence to this answer).
'we' becomes 'us'.
'rio'+'to'+'us'='RIOTOUS'
'see' is the link.
Can you help me to learn more?
(Other definitions for riotous that I've seen before include "Hilariously funny" , "Rollicking" , "Artificial fabric" , "Wild, disorderly" , "wild and unruly" .)