Vintage Times puzzle (4)
I believe the answer is:
crux
'puzzle' is the definition.
(thesaurus)
'vintage times' is the wordplay.
'vintage' becomes 'cru' (e.g. grand cru).
'times' becomes 'x' (multiplication sign).
'cru'+'x'='CRUX'
(Other definitions for crux that I've seen before include "Key point" , "Essence or gist" , "Main point (of the matter)" , "Point of difficulty" , "Most important point at issue" .)