Source of food designed to deter boys (6,3)
I believe the answer is:
oyster bed
'source of food' is the definition.
'oyster bed' can be an answer for 'source' (I have seen 'Source of pearls ' mean 'oyster bed' so perhaps 'source' could also mean 'oyster bed'). I am unsure of the 'of food' bit.
'designed to deter boys' is the wordplay.
'designed' indicates anagramming the letters (designed with the letters).
'deter'+'boys'='deterboys'
'deterboys' is an anagram of 'OYSTER-BED'.
Can you help me to learn more?
(Other definitions for oyster bed that I've seen before include "Source of pearls" , "A source of seafood" , "breeding ground" , "seafood supplier" , "stew, perhaps" .)