Plant plants killing time in vacated area (6)
I believe the answer is:
acacia
'plant plants' is the definition.
'acacia' can be an answer for 'plant' (I've seen this before). I am not sure about the 'plants' bit.
'killing time in vacated area' is the wordplay.
'killing time in' becomes 'acac' (I am not sure about this - if you are sure you should believe this answer much more).
'vacated' says to hollow out the word (remove centre letters) (internal letters vacate the word).
'area' becomes 'Ionia' (Ionia is an example).
'ionia' with its centre taken out is 'ia'.
'acac'+'ia'='ACACIA'
Can you help me to learn more?
(Other definitions for acacia that I've seen before include "Thorny flowering shrub" , "Australian shrub" , "Garden shrub, also known as wattle" , "Tropical tree, inc. mimosa, wattle" , "(Sub)tropical shrub with yellow or white flowers - wattle" .)