Sweets that go bad when put in water (7)
I believe the answer is:
toffees
'sweets that go' is the definition.
'toffees' can be an answer for 'sweets' (toffee is a kind of sweet). I am not certain of the rest of the definition.
'bad when put in water' is the wordplay.
'bad' becomes 'off' (eg meat that's gone off is bad).
'when' becomes 'e' (I've seen this in other clues).
'put in' is an insertion indicator.
'water' becomes 'tes' (I can't explain this - if you can you should give a lot more credence to this answer).
'off'+'e'='offe'
'offe' placed into 'tes' is 'TOFFEES'.
Can you help me to learn more?
(Other definitions for toffees that I've seen before include "Caramels" , "Sweets" .)