The plant will shoot, given water (9)
I believe the answer is:
speedwell
'the plant' is the definition.
(speedwell is a kind of plant)
'shoot given water' is the wordplay.
'shoot given' becomes 'speed' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'water' becomes 'well water' (well water is a kind of water).
'speed'+'well'='SPEEDWELL'
'will' is the link.
Can you help me to learn more?
(Other definitions for speedwell that I've seen before include "bloomer?" , "Small blue flower of the genus veronica" , "Flowering plant" , "Small creeping herbaceous plant with blue or pink flowers" , "Small plant, veronica" .)