Small boy full of strange ideas for a dish (4,5)
I believe the answer is:
side salad
'a dish' is the definition.
(I've seen this before)
'small boy full of strange ideas' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'boy' becomes 'lad' (lad is a kind of boy**).
'full of' means one lot of letters goes inside another.
'strange' indicates anagramming the letters.
's'+'lad'='slad'
'ideas' is an anagram of 'idesa'.
'slad' enclosing 'idesa' is 'SIDE SALAD'.
'for' is the link.
(Another definition for side salad that I've seen is " Extra dish of lettuce, tomato etc?".)