Small fly discovered amid geraniums (5)
I believe the answer is:
midge
'small fly' is the definition.
(I've seen this before)
'discovered amid geraniums' is the wordplay.
'discovered' indicates a hidden word (remove the letters covering the answer in the clue).
'MIDGE' can be found hidden inside 'amid geraniums'.
(Other definitions for midge that I've seen before include "Small swarming biting insect" , "Two-winged fly" , "Gnat" , "Tiny swarming fly" , "Be an obstacle" .)