Evergreen version of pea, encased in pot (8,5)
I believe the answer is:
Here is my best explanation:
'evergreen' is the definition.
'version of pea encased in pot' is the wordplay.
'version of' is an anagram indicator.
'in' indicates putting letters inside.
'pot' becomes 'jar'.
'peaencased' anagrammed gives 'apaneseced'.
'apaneseced' going into 'jar' is 'JAPANESE CEDAR'.