A bit of alcohol's appropriate for children, silly (4)
I believe the answer is:
unit
'a bit' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe there's a link between them I don't understand?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for unit that I've seen before include "Kitchen fitment" , "Small group" , "army group" , "Entity, system; component group" , "Individual thing or group regarded as complete" .)