A flower pleased Louis, perhaps (9)
I believe the answer is:
gladiolus
'a flower' is the definition.
(I've seen this before)
'pleased louis perhaps' is the wordplay.
'pleased' becomes 'glad' (similar in meaning).
'perhaps' indicates an anagram.
'louis' with letters rearranged gives 'iolus'.
'glad'+'iolus'='GLADIOLUS'
(Other definitions for gladiolus that I've seen before include "Flower" , "Plant of iris family" .)