Dye-producing plant doing badly, I admitted (6)
I believe the answer is:
indigo
'dye-producing plant' is the definition.
(plant which produces indigo dye)
'doing badly i admitted' is the wordplay.
'badly' indicates an anagram.
'admitted' means one lot of letters goes inside another.
'doing' is an anagram of 'indgo'.
'indgo' going around 'i' is 'INDIGO'.
(Other definitions for indigo that I've seen before include "Ellington's Mood" , "Mood - (Duke Ellington)" , "Tropical plant" , "A deep blue dye or colour" , "Spectral colour" .)