Eucalyptus bush, one seen in trendy pub (8)

'eucalyptus' is the definition.
(I have seen 'Australian eucalyptus ' mean 'coolibar' so perhaps 'eucalyptus' could also mean 'coolibar')

'one seen in trendy pub' is the wordplay.
'one' becomes 'i' (Roman numeral).
'seen in' is an insertion indicator.
'trendy' becomes 'cool' (I am not sure about this - if you are sure you should believe this answer much more).
'pub' becomes 'bar' (both are drinking establishments).
'cool'+'bar'='coolbar'
'i' put inside 'coolbar' is 'COOLIBAR'.

'bush' acts as a link.
I am not very happy about this link. It may be part of another bit of the clue.

Can you help me to learn more?