A mere craze due to finish and pass away (4)
I believe the answer is:
fade
'pass away' is the definition.
(thesaurus)
'a mere craze due to finish' is the wordplay.
'a mere craze' becomes 'fad' (synonyms. I am not sure about the 'mere' bit.).
'to finish' indicates one should take the final letters.
The last letter of 'due' is 'e'.
'fad'+'e'='FADE'
'and' acts as a link.
Can you help me to learn more?
(Other definitions for fade that I've seen before include "Lose colour gradually" , "flag" , "Bleach or decline" , "Gradually disappear from view" , "Grow dull" .)