Runs away eating son's sweets (8)
I believe the answer is:
desserts
'sweets' is the definition.
(sweet can mean a dessert or pudding)
'runs away eating son's' is the wordplay.
'runs away' becomes 'deserts' (I've seen this in another clue).
'eating' is an insertion indicator.
'deserts' placed around 's' is 'DESSERTS'.
(Other definitions for desserts that I've seen before include "Puddings" , "fools, perhaps?" , "Sweet courses of meal" , "That may be cobblers" , "Final courses" .)