Mamma Mia finally shown in French port (6)
I believe the answer is:
breast
'mamma' is the definition.
(breast is a kind of mamma)
'mia finally shown in french port' is the wordplay.
'finally' indicates one should take the final letters.
'shown in' is an insertion indicator.
'french port' becomes 'brest' (a port city in brittany).
The final letter of 'mia' is 'a'.
'a' inserted within 'brest' is 'BREAST'.
(Other definitions for breast that I've seen before include "Front of upper body" , "Mamma" , "Confront" , "Outer thorax" , "Front of the trunk" .)