Soldiers on charge initially concealed bloomer (6)
I believe the answer is:
orchid
'bloomer' is the definition.
(orchid is a kind of flowering plant)
'soldiers on charge initially concealed' is the wordplay.
'soldiers' becomes 'or' (Other Rank).
'on' is a charade indicator (letters next to each other).
'initially' suggests taking the first letters.
'concealed' becomes 'hid' ('hide' can be a synonym of 'conceal'**).
The initial letter of 'charge' is 'c'.
'or'+'c'+'hid'='ORCHID'
(Other definitions for orchid that I've seen before include "Bee, lady, butterfly or slipper -" , "Plant with beautiful, unusually shaped flowers" , "Blooming" , "Exotic plant with unusually shaped flowers of vivid colour" , "elaborate bloomer" .)