One who entertains son during baking (4)
I believe the answer is:
host
'one who entertains' is the definition.
(I've seen this before)
'son during baking' is the wordplay.
'son' becomes 's'.
'during' is an insertion indicator.
'baking' becomes 'hot' ('hot' can be similar in meaning to 'baking').
's' placed into 'hot' is 'HOST'.
(Other definitions for host that I've seen before include "One entertaining, large number" , "Party-giver" , "One entertains guests" , "Large crowd" , "Crowd-entertainer" .)