Prophet endlessly devouring American dessert (6)
I believe the answer is:
mousse
'dessert' is the definition.
(I know that mousse is a type of dessert)
'prophet endlessly devouring american' is the wordplay.
'prophet endlessly' becomes 'mose' (I can't explain this - if you can you should give a lot more credence to this answer).
'devouring' is an insertion indicator.
'american' becomes 'US' (abbreviation for United States).
'mose' going around 'us' is 'MOUSSE'.
Can you help me to learn more?
(Other definitions for mousse that I've seen before include "A hair dressing; a creamy sweet" , "Gel" , "F" , "Whipped cream dessert" , "A dessert, or creamy substance used to style hair" .)