Part of bulb cracked (5)
I believe the answer is:
clove
I believe this clue is a double definition.
'part of bulb' is the first definition.
'cracked' is the second definition.
(clove can mean split or cleaved)
(Other definitions for clove that I've seen before include "caused separation" , "Aromatic bud" , "A spice; a garlic bulb" , "Cut" , "Flower bud used as a spice" .)