Plant like cuckoo pint (4)
I believe the answer is:
arum
'plant like cuckoo pint' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for arum that I've seen before include "Plant like cuckoo pint" , "genus of plants" , "Cuckoo pint is one such" , "Type of plant, lily perhaps" , "Type of 1 Across" .)