Old-school (5)
I believe the answer is:
retro
'old-school' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for retro that I've seen before include "Slangy adjective for harking back to the past" , "Old-fashioned style" , "bit of nostalgia" , "suggestive of past" , "Fashion of yesteryear" .)