The French lunch starts surrounded by soy only (6)
I believe the answer is:
solely
'only' is the definition.
(I know that only can be written as solely)
'the french lunch starts surrounded by soy' is the wordplay.
'the french' becomes 'le' ('the' in French).
'starts' indicates taking the first letters.
'surrounded by' means one lot of letters goes inside another.
The first letter of 'lunch' is 'l'.
'le'+'l'='lel'
'lel' going inside 'soy' is 'SOLELY'.
(Other definitions for solely that I've seen before include "alone" , "Exclusively, only" , "nowhere else?" , "Singly" , "Singularly" .)