Dad eats it with ultimately moist bread (5)
I believe the answer is:
pitta
'bread' is the definition.
(I've seen this before)
'dad eats it with ultimately moist' is the wordplay.
'dad' becomes 'pa' (synonyms).
'eats' is an insertion indicator.
'with' is an insertion indicator.
'ultimately' says to take the final letters.
The last letter of 'moist' is 't'.
'it' placed around 't' is 'itt'.
'pa' enclosing 'itt' is 'PITTA'.
(Other definitions for pitta that I've seen before include "(E.g. Greek) bread" , "Slightly leavened bread" , "Type of flatbread" , "Type of flat bread that's split to hold a filling" , "Flat sort of bread" .)