Charlie unfortunately keeping one in French port (6)
I believe the answer is:
calais
'french port' is the definition.
(Calais is a port in France)
'charlie unfortunately keeping one' is the wordplay.
'charlie' becomes 'C' (phonetic alphabet).
'unfortunately' becomes 'alas' ('alas' is used to express regret).
'keeping' means one lot of letters goes inside another (some letters kept inside).
'one' becomes 'i' (Roman numeral).
'alas' going around 'i' is 'alais'.
'c'+'alais'='CALAIS'
'in' is the link.
(Other definitions for calais that I've seen before include "Northern French port" , "end of the tunnel" , "Nearest French port to England" , "French Channel port" , "Mary Tudor said it would be found "lying in my heart"" .)