Send first of trainees in to clean each plant (5,3)
I believe the answer is:
sweet pea
'plant' is the definition.
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for sweet pea that I've seen before include "Garden plant with pastel-coloured flowers" , "Perfumed climber" , "Fragrant flower" , "Celestial source of fluctuating radio waves" , "Pew tease (anag) - flower" .)