Plant group in borders of shady area (7)
I believe the answer is:
syringa
'plant' is the definition.
The answer is an example.
'group in borders of shady area' is the wordplay.
'group' becomes 'ring' (a ring is a criminal organisation).
'in' indicates putting letters inside.
'borders of' means to remove the middle letters.
'area' becomes 'a' (maths abbreviation).
'shady' with its middle removed is 'sy'.
'sy'+'a'='sya'
'ring' inserted into 'sya' is 'SYRINGA'.
(Other definitions for syringa that I've seen before include "Is angry (anag.)" , "Lilac genus" , "Lilac (popularly, orange blossom)" , "Flowering shrub" , "Mock-orange plant" .)