Lily close to gardenia, unusual (4)
I believe the answer is:
arum
'lily' is the definition.
(a type of lily)
'close to gardenia unusual' is the wordplay.
'close to' indicates one should take the final letters (the close/ending of).
'unusual' becomes 'rum' (I've seen this before).
The last letter of 'gardenia' is 'a'.
'a'+'rum'='ARUM'
(Other definitions for arum that I've seen before include "Cuckoo-pint" , "Cuckoo pint genus" , "plant with a white spathe" , "Plant like cuckoo pint" , "Plant with small flowers and arrow-shaped leaves - kind of lily" .)