The most common and most likely answer to this crossword clue is the 5 letter word RETRO
I've seen this crossword clue in The Times
R
E
T
R
O
More clues leading to the result RETRO
- Old-fashioned beer brought back without pressure
- Garret room to some extent reminiscent of past
- Some treasure trove appearing from the past
- Old-fashioned railway system runs for miles
- Underground gets new head, consciously old-fashioned
- Redolent of old caretaker discharging power when upset
- Backward-looking group of reporters with a bygone style
- Period concerned with terror, oddly
- Yesteryear’s style covered by reporters looking back
- Some reporters reverted to an earlier style
Buddy explains!

The straight part
We know that "Old-fashioned" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case old-fashioned = retro.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does RETRO mean?
RETRO noun- Past fashions or trends.
- Of, or relating to, the past, past times, or the way things were.
- Affecting things past; retroactive, ex post facto.
- A small rocket engine on a larger rocket or spacecraft, designed to slow or reverse its motion.
- An exhibition of works from an extended period of an artist's activity.