Crumble one type of bread (4)
I believe the answer is:
roti
'type of bread' is the definition.
'roti' can be an answer for 'bread' (roti is a type of bread). I'm unsure of the 'type of' bit.
'crumble one' is the wordplay.
'crumble' becomes 'rot' (I've seen this in another clue).
'one' becomes 'i' (Roman numeral).
'rot'+'i'='ROTI'
Can you help me to learn more?
(Other definitions for roti that I've seen before include "Indian bread (not naan)" , "Indian bread cooked on a griddle" , "Indian flatbread" , "Indian flat round bread" , "spicy sandwich" .)