Young son and cook going round arcade (5,3)
I believe the answer is:
small fry
'young' is the definition.
(thesaurus)
'son and cook going round arcade' is the wordplay.
'son' becomes 's'.
'and' is a charade indicator (letters next to each other).
'cook' becomes 'fry' (I've seen this before).
'going round' indicates putting letters inside.
'arcade' becomes 'mall'.
's'+'fry'='sfry'
'sfry' going around 'mall' is 'SMALL-FRY'.
(Other definitions for small fry that I've seen before include "young children" , "Not the full English breakfast" , "Little fish or folk" , "Young ones in school" , "people of little importance" .)