Flying mammal ate one worm, perhaps (4)
I believe the answer is:
bait
'worm perhaps' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps you can see a link between them that I don't see?
'flying mammal ate one' is the wordplay.
'flying mammal' becomes 'bat' (I've seen this before).
'ate' indicates putting letters inside.
'one' becomes 'i' (Roman numeral).
'bat' placed around 'i' is 'BAIT'.
Can you help me to learn more?
(Other definitions for bait that I've seen before include "Taunt; enticement" , "Allurement" , "Food used as lure" , "Food to entice fish; taunt" , "N in radio comms" .)