Spinster can't be a hit! (4)
I believe the answer is:
miss
'spinster' is the definition.
(thesaurus)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for miss that I've seen before include "Young girl" , "Fail to attend (event)" , "Austria/Italy region" , "Fail to hit; girl" , "Fail to hit (something)" .)