Drop, then fix, mug (8)
I believe the answer is:
dipstick
'mug' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'drop then fix' is the wordplay.
'drop' becomes 'dip' (I've seen this before).
'then fix' becomes 'stick' (sticking is a kind of fixing. I am not sure about the 'then' bit.).
'dip'+'stick'='DIPSTICK'
Can you help me to learn more?
(Other definitions for dipstick that I've seen before include "Oil gauge" , "plunged into engine oil?" , "one concealed under bonnet?" , "Stupid person" , "shower of liquid" .)