Short girl crossing European river by a rosaceous shrub (8)
I believe the answer is:
japonica
'rosaceous shrub' is the definition.
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for japonica that I've seen before include "Shrub with yellowish fruit" , "plant" , "Asian shrub of the rose family - I cap Joan (anag)" , "Camellia" , "Asian shrub of the rose family, with showy flowers" .)