Primitive plant (4)
I believe the answer is:
alga
'primitive plant' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for alga that I've seen before include "from ore found locally" , "Possibly tangle" , "Simple, non-flowering, aquatic plant" , "Simple plant, plankton or seaweed say" , "Irish moss, for example" .)