Like Simon or Herb (6)
I believe the answer is:
simple
This clue is a double definition.
'like simon' is the first definition.
(reference to nursery rhyme Simple Simon)
'herb' is the second definition.
(simple is a kind of herb)
'or' acts as a link.
(Other definitions for simple that I've seen before include "Naive" , "Impels to be plain" , "Easy; plain" , "The opposite of difficult or elaborate" , "Uncomplicated; herb" .)