Stimulate flower with uranium (5)
I believe the answer is:
rouse
'stimulate' is the definition.
(I've seen this in another clue)
'flower with uranium' is the wordplay.
'flower' becomes 'rose' (I've seen this in other clues).
'with' indicates putting letters inside.
'uranium' becomes 'U' (U is the chemical symbol for uranium).
'rose' placed around 'u' is 'ROUSE'.
(Other definitions for rouse that I've seen before include "Bumper" , "To start" , "Excite; awaken" , "Make angry" , "Stir from inactivity" .)