Shoot number, with military exercise almost completed (7)
I believe the answer is:
tendril
'shoot' is the definition.
(a shoot from a plant)
'number with military exercise almost completed' is the wordplay.
'number' becomes 'ten' (ten is a kind of number).
'with' says to put letters next to each other.
'military exercise' becomes 'drill' (I've seen this in another clue).
'almost completed' means to remove the last letter.
'drill' with its final letter taken away is 'dril'.
'ten'+'dril'='TENDRIL'
(Other definitions for tendril that I've seen before include "Climbing plant's supporter" , "Part of twining plant" , "Slender stem on twining plants" , "Feature of plant" , "Climbing plant's gripper" .)