Buffoons regularly picked out flying saucers (4)
I believe the answer is:
ufos
'flying saucers' is the definition.
('UFO' can be a synonym of 'flying saucer')
'buffoons regularly picked out' is the wordplay.
'regularly picked out' means one should take alternating letters.
The alternating letters of 'buffoons' are 'UFOS'.
(Other definitions for ufos that I've seen before include "Supposed spaceships" , "Unauthorised traffic from outer space?" , "Potential alien craft" , "Supposed alien craft" , "Strange aerial objects" .)