Shrub came back to life — army mobilised! (8)
I believe the answer is:
rosemary
'shrub' is the definition.
(I have seen 'Aromatic shrub' mean 'rosemary' so perhaps 'shrub' could also mean 'rosemary')
'came back to life army mobilised' is the wordplay.
'came back to life' becomes 'rose' (as in rising from the dead).
'mobilised' indicates anagramming the letters (I've seen this in other clues).
'army' is an anagram of 'mary'.
'rose'+'mary'='ROSEMARY'
(Other definitions for rosemary that I've seen before include "Herb - girl's name" , "Name of girl or herb" , "Aromatic shrub" , "Plant" , "Herb for remembrance" .)