Type of brush undergrowth (5)
I believe the answer is:
shrub
'undergrowth' is the definition.
The answer and definition can be both plants as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'type of brush' is the wordplay.
'type of' indicates anagramming the letters (I've seen 'type' mean this).
'brush' with letters rearranged gives 'SHRUB'.
Can you help me to learn more?
(Other definitions for shrub that I've seen before include "Low woody perennial type of plant" , "Small woody plant" , "Rose, perhaps" , "Bushy plant" , "Woody plant smaller than a tree" .)