Dad has soft food (3)
I believe the answer is:
pap
'food' is the definition.
(pap is a kind of food)
'dad has soft' is the wordplay.
'dad' becomes 'pa' ('pa' can be a synonym of 'dad').
'has' means one lot of letters go next to another.
'soft' becomes 'p' (musical abbreviation for 'piano'**).
'pa'+'p'='PAP'
(Other definitions for pap that I've seen before include "Bland soft food" , "Mushy food for children or invalids" , "Palindromic food for infants" , "mindless entertainment" , "Dog with a camera" .)