Article about spies in plant (6)
I believe the answer is:
acacia
'plant' is the definition.
(acacia is a kind of plant)
'article about spies' is the wordplay.
'article' becomes 'a' (indefinite article).
'about' becomes 'ca' (abbreviation for 'circa'**).
'spies' becomes 'cia'.
'a'+'ca'+'cia'='ACACIA'
'in' acts as a link.
(Other definitions for acacia that I've seen before include "Australian shrub" , "Australian tree" , "Tropical shrub" , "Wattle that grows" , "(Sub)tropical shrub with yellow or white flowers - wattle" .)