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 subsidiary indication.
'version of' is an anagram indicator.
'in' indicates putting letters inside.
'pot' becomes 'jar'.
'peaencased' anagrammed gives 'apaneseced'.
'apaneseced' placed into 'jar' is 'japanesecedar'.