Discovered parcel of asparagus seed (3)
I believe the answer is:
pea
'seed' is the definition.
(I've seen this before)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for pea that I've seen before include "registered by princess in bed" , "It grows in 23 Down" , "It may climb frame" , "Ape this plant awkwardly" , "Leguminous vegetable" .)