Stick supporting middle of blue flower (5)
I believe the answer is:
lupin
'flower' is the definition.
(I've seen this before)
'stick supporting middle of blue' is the wordplay.
'stick' becomes 'pin' ('pin' can be a synonym of 'stick'**).
'supporting' means one lot of letters go next to another (in a down clue, some letters go below others).
'middle of' says to take the centre.
The central letters of 'blue' are 'lu'.
'pin' put after 'lu' is 'LUPIN'.
(Other definitions for lupin that I've seen before include "Plant with erect spikes of usually purplish-blue flowers" , "Spiked flower" , "bloomer" , "9 [BLOOM]" , "Pea relative with tall spikes of flowers" .)