Cake for junior girl scout (7)
I believe the answer is:
brownie
I believe this is a double definition.
'cake' is the first definition.
(brownie is a kind of cake)
'junior girl scout' is the second definition.
(I've seen this before)
'for' acts as a link.
(Other definitions for brownie that I've seen before include "sweet thing" , "Junior Girl Scout" , "confection" , "Benevolent helper" , "Junior member of girl's movement ..." .)