Flower in pail, up inside (5)
I believe the answer is:
lupin
'flower' is the definition.
(I've seen this before)
'in pail up inside' is the wordplay.
'in' indicates a hidden word.
'LUPIN' is hidden in the letters of 'pail up inside'.
(Other definitions for lupin that I've seen before include "Plant with erect spikes of usually purplish-blue flowers" , "bloomer" , "Plant with flowers on long spikes" , "Flower of pea family" , "Spiked flower" .)