Plant often given water (5)
I believe the answer is:
cress
'plant' is the definition.
(cress plant is a kind of plant)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for cress that I've seen before include "Salad sprouts" , "Toll of bell" , "Plant with leaves used in salad or as garnish" , "Cruciferous salad plant" , "bit of salad" .)