See you in port on Red Sea, nude (7)
I believe the answer is:
cheerio
'see you' is the definition.
(I've seen this before)
'port on red sea nude' is the wordplay.
'port' becomes 'rio' (Rio de Janeiro is a port).
'on' means one lot of letters go next to another.
'red' becomes 'che' (as in Che Guevara, a communist or 'red').
'nude' indicates the central letters (the word is stripped of its outer letters).
The central letter of 'sea' is 'e'.
'che'+'e'='chee'
'rio' after 'chee' is 'CHEERIO'.
'in' acts as a link.
(Other definitions for cheerio that I've seen before include "Ta-ta" , "Say this before drinking" , "Bye-bye" , "Expression used when leaving" , "Farewell - drinking toast" .)