Crusty roll, one consumed by peevish worker, perhaps (9)
I believe the answer is:
croissant
'crusty roll' is the definition.
'croissant' can be an answer for 'roll' (croissant is a kind of roll). I am not certain of the 'crusty' bit.
'one consumed by peevish worker perhaps' is the wordplay.
'one' becomes 'i' (Roman numeral).
'consumed by' means one lot of letters goes inside another.
'peevish' becomes 'cross' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'worker perhaps' becomes 'ant' (worker is a type of ant).
'i' inserted within 'cross' is 'croiss'.
'croiss'+'ant'='CROISSANT'
Can you help me to learn more?
(Other definitions for croissant that I've seen before include "food item" , "French pastry" , "A rich crescrent-shaped bread roll" , "Breakfast pastry" , "French breakfast food" .)