A fancy earpiece will not last long (4)
I believe the answer is:
fade
'will not last long' is the definition.
I can't tell whether this definition defines the answer.
'a fancy earpiece' is the wordplay.
'a fancy' becomes 'fad' (I've seen this in other clues).
'earpiece' becomes 'e' (this could be a standard abbreviation of which I'm unaware).
'fad'+'e'='FADE'
Can you help me to learn more?
(Other definitions for fade that I've seen before include "Grow faint and disappear" , "Gradually grow faint" , "Lose strength" , "Droop" , "Gradually disappear from view" .)