Plants making mourning clothes (5)
I believe the answer is:
weeds
This clue might be a double definition.
'plants making' is the first definition.
'weeds' can be an answer for 'plants' (I have seen 'Unwanted plants ' mean 'weeds' so perhaps 'plants' could also mean 'weeds'). I'm not certain of the 'making' bit.
'mourning clothes' is the second definition.
(I've seen this before)
Can you help me to learn more?
(Other definitions for weeds that I've seen before include "Wild plants; mourning garb" , "Unwanted plants" , "Black garments once worn by widows" , "mourning clothes" , "Are they worn by widows in the garden?" .)