Plant with dope taken in by agency (6)
I believe the answer is:
cassia
'plant' is the definition.
The answer is an example.
'dope taken in by agency' is the wordplay.
'dope' becomes 'ass'.
'taken in by' indicates putting letters inside.
'agency' becomes 'cia' (CIA is an example).
'ass' placed into 'cia' is 'CASSIA'.
'with' is the link.
(Other definitions for cassia that I've seen before include "Senna-producing tree" , "Chinese tree with aromatic bark - is a sac (anag)" , "Tree producing senna" , "Source of senna" , "Tree providing senna" .)