Duck circling extremely strange plant (6)
I believe the answer is:
teasel
'plant' is the definition.
(teasel is a kind of plant)
'duck circling extremely strange' is the wordplay.
'duck' becomes 'teal' (teal is a type of duck).
'circling' is an insertion indicator (circling can mean going around or containing).
'extremely' suggests removing the centre (letters on the extremes of the word are used).
'strange' with its centre removed is 'se'.
'teal' going around 'se' is 'TEASEL'.
(Other definitions for teasel that I've seen before include "Spiny flower head" , "Prickly wild plant" , "Dried flower head" , "Plant with spiny purple flower heads" , "Prickly plant (S, not Z)" .)