Sloshed gun-aimer makes bloomer (8)
I believe the answer is:
geranium
'bloomer' is the definition.
(I have seen 'A bloomer' mean 'geranium' so perhaps 'bloomer' could also mean 'geranium')
'sloshed gun-aimer' is the wordplay.
'sloshed' indicates an anagram.
'gun'+'aimer'='gunaimer'
'gunaimer' anagrammed gives 'GERANIUM'.
'makes' is the link.
(Other definitions for geranium that I've seen before include "A bloomer" , "Cultivated pelargonium" , "Popular flowering pot plant" , "Flower confused with pelargonium" , "Cranesbill plant" .)