Prickly seedcase
'prickly seedcase' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for burr that I've seen before include "Seed vessel" , "Prickly seeds" , "(Sound made by) drill or dialect" , "Prickly, clinging seed-case" , "Type of seed with short stiff bristles or hooks" .)
'prickly seedcase' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for bur that I've seen before include "Prickly seed case" , "sticker" , "Clinging seed case" , "Seed-case" , "small drill" .)