Happy couple in Rome crossing banks of oriental flowers (8)
I believe the answer is:
gladioli
'flowers' is the definition.
(I've seen this before)
'happy couple in rome crossing banks of oriental' is the wordplay.
'happy' becomes 'glad' ('glad' can be a synonym of 'happy').
'couple in rome' becomes 'ii' (two in Roman numerals).
'crossing' indicates putting letters inside.
'banks of' says to hollow out the word (remove centre letters) (the banks are the sides of the word).
'oriental' with its centre removed is 'ol'.
'ii' going around 'ol' is 'ioli'.
'glad'+'ioli'='GLADIOLI'
(Other definitions for gladioli that I've seen before include "Did the Iliad log out these flowers?" , "bloomers!" , "Garden flowers with brightly coloured spikes" , "Tall garden flowers" , "Plants with tall flower spikes" .)