Memsahib is customarily holding flower (8)
I believe the answer is:
hibiscus
'flower' is the definition.
(I have seen 'Colourful flower ' mean 'hibiscus' so perhaps 'flower' could also mean 'hibiscus')
'memsahib is customarily holding' is the wordplay.
'holding' indicates the answer is hidden within the clue.
'HIBISCUS' can be found hidden inside 'memsahib is customarily'.
(Other definitions for hibiscus that I've seen before include "Plant of the mallow family - such ibis (anag)" , "Large colourful flower" , "The rose mallow" , "Malaysian national symbol" , "Genus of mostly tropical plants" .)