Flower originated beneath quiet border (8)
I believe the answer is:
primrose
'flower' is the definition.
(thesaurus)
'originated beneath quiet border' is the wordplay.
'originated' becomes 'rose'.
'beneath' is a charade indicator (letters next to each other) (in a down clue).
'quiet' becomes 'p' (music symbol for 'piano').
'border' becomes 'rim' (I've seen this before**).
'p'+'rim'='prim'
'rose' put after 'prim' is 'PRIMROSE'.
(Other definitions for primrose that I've seen before include "Rip morse up to find the flower" , "grows wild" , "Spring woodland flower" , "Wild flower (connected to an attractive path?)" , "Woodland plant with yellow flowers in spring" .)