Crack inside tree from the east producing shrub (6)
I believe the answer is:
myrtle
'shrub' is the definition.
(myrtle is a kind of shrub)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for myrtle that I've seen before include "Shrub with purple-black oval berries" , "Evergreen shrub with dark purple berries" , "Fragrant evergreen shrub" , "Plant with aromatic blue-black berries" , "Evergreen shrub - try elm (anag)" .)