Traditional (6)
'traditional' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for classic that I've seen before include "Work of established excellence (7)" , "Eg, screw thread" , "work of the highest quality" , "Model" , "Relating to early Greek and Latin writers" .)
'traditional' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for old school that I've seen before include "In Westminster" , "Of people favouring traditional ideas" , "group that has no small fry in it?" , "Those who think traditionally" , "a bunch of conservative types" .)
'traditional' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for formal that I've seen before include "Like court dress, perhaps" , "conventionally correct" , "Punctilious" , "Official; stiff" , "black tie" .)
'traditional' is the definition.
(similar in meaning)
This is all the clue.
(Other definitions for orthodox that I've seen before include "Standard" , "Conventional, normal" , "Conformist" , "Conforming with established doctrine" , "Conservative" .)