I ring up about the plant (5)
I believe the answer is:
lilac
'the plant' is the definition.
The answer is an example.
'i ring up about' is the wordplay.
'i ring' becomes 'lil' (I've seen this in other clues).
'up' is a reversal indicator (in down clue: letters go upwards).
'about' becomes 'ca' (abbreviation for 'circa').
'ca' written backwards gives 'ac'.
'lil'+'ac'='LILAC'
(Other definitions for lilac that I've seen before include "Flowering tree of the olive family" , "Shrub or small tree with fragrant blossom" , "Syringa vulgaris, light purple in colour" , "Fragrant, pale purple flower" , "Shrub with fragment purple or white flowers" .)