Dad and son go for cake (6)
I believe the answer is:
pastry
'for cake' is the definition.
(type of baked good)
'dad and son go' is the wordplay.
'dad' becomes 'pa' (both can mean one's father).
'and' says to put letters next to each other.
'son' becomes 's' (genealogical abbreviation for son).
'go' becomes 'try' (both can mean an attempt).
'pa'+'s'+'try'='PASTRY'
(Other definitions for pastry that I've seen before include "Eg, pie crust" , "Eg, Danish" , "Dough used in pie-cases" , "Dough of flour, water and shortening" , "Cake - tart" .)