Short-lived English public house largely green (9)
I believe the answer is:
ephemeral
'short-lived' is the definition.
(synonyms)
'english public house largely green' is the wordplay.
'english' becomes 'E' (abbreviation).
'public house' becomes 'ph' (abbreviation).
'largely' means to remove the last letter (most but not all of the letters).
'green' becomes 'emerald' (emerald is a shade of green).
'emerald' with its last letter taken off is 'emeral'.
'e'+'ph'+'emeral'='EPHEMERAL'
(Other definitions for ephemeral that I've seen before include "Fleeting, lasting only a short time" , "staying for a little while" , "A mere help (anag) - short-lived" , "Short-lived, passing quickly" , "Fugitive" .)