Coffee seller changing taps for Lily (5)
I believe the answer is:
hosta
'lily' is the definition.
(hosta is a type of lily)
I don't understand how the rest of the clue works.
(Other definitions for hosta that I've seen before include "found in a bed, perhaps" , "Plant that likes shade" , "flowering plant" , "Athos (anag) - perennial plant" , "Garden plant with ornamental foliage" .)