Flower in boozer beset by Brussels taxes (9)
I believe the answer is:
euphrates
'flower' is the definition.
(Euphrates River is an example)
'boozer beset by brussels taxes' is the wordplay.
'boozer' becomes 'ph' (I am not sure about this - if you are sure you should believe this answer much more).
'beset by' means one lot of letters goes inside another ('beset' could historically mean 'cover').
'brussels' becomes 'EU' (European Parliament is based in Brussels).
'taxes' becomes 'rates' (rate is a kind of tax).
'eu'+'rates'='eurates'
'ph' put within 'eurates' is 'EUPHRATES'.
'in' is the link.
Can you help me to learn more?
(Other definitions for euphrates that I've seen before include "running water in SW Asia" , "River which joins Tigris in Iraq" , "River joining the Tigris" , "current in the Middle East?" , "Asian river" .)