Flashy fellow, possibly with a screw loose? (5)
I believe the answer is:
robot
'screw loose?' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for robot that I've seen before include "Automation" , "Automaton or sci-fi creature" , "programmed servant" , "Mechanism that moves automatically" , "Man-made man - man-made machine" .)