Prime minister once having answer for bread (5)
I believe the answer is:
pitta
'bread' is the definition.
(I've seen this before)
'prime minister once having answer' is the wordplay.
'prime minister once' becomes 'pitt' (William Pitt).
'having' says to put letters next to each other.
'answer' becomes 'a' (abbreviation eg in Q and A).
'pitt'+'a'='PITTA'
'for' acts as a link.
(Other definitions for pitta that I've seen before include "Flat sort of bread" , "Middle Eastern bread" , "Flat bread that's split to take a filling" , "Flat hollow unleavened bread" , "Type of flatbread" .)