Dessert in Finland mostly served up with peel of star-apple (6)
I believe the answer is:
mousse
'dessert' is the definition.
(mousse is a kind of dessert)
'finland mostly served up with peel of star-apple' is the wordplay.
'finland' becomes 'suomi' (Finnish name for Finland).
'mostly' means to remove the last letter.
'served up' says the letters should be written backwards.
'with' is a charade indicator (letters next to each other).
'peel of star apple' becomes 'se' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'suomi' with its last letter removed is 'suom'.
'suom' written backwards gives 'mous'.
'mous'+'se'='MOUSSE'
'in' acts as a link.
(Other definitions for mousse that I've seen before include "Whipped creamy dessert" , "A hair dressing; a creamy sweet" , "Creamy dish" , "Foamy dish" , "Frothy, creamy dessert" .)