Flower border presented in plain language (8)
I believe the answer is:
primrose
'flower' is the definition.
(thesaurus)
'border presented in plain language' is the wordplay.
'border' becomes 'rim' (I've seen this before).
'presented in' means one lot of letters goes inside another.
'plain language' becomes 'prose' (I've seen this in other clues).
'rim' going inside 'prose' is 'PRIMROSE'.
(Other definitions for primrose that I've seen before include "Wild flower (connected to an attractive path?)" , "Early spring flower" , "Yellowish" , "Yellow spring flower from promiser" , "Pale yellow flower" .)