The most common and most likely answer to this crossword clue is the 6 letter word FOSSIL
I've seen this crossword clue in The Daily Telegraph
F
O
S
S
I
L
More clues leading to the result FOSSIL
- Dinosaur in Komsomol is so far to the left
- Old relic sons wrapped in thin metallic sheet
- Prehistoric relic sons wrapped in metallic sheet
- Geological evidence from UFOs? Silly
- Sword with Nazi inscription, museum piece
- Chapel is so fortunate to hold returned relic
- Ancient 3 fellow East German left
- Relic of saints captured in defeat
- Metal encasing small orris root is an item of interest to palaeontologists
- Preserved part of ship in protective coating
Buddy explains!

The straight part
We know that "something likely to be extracted" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case something likely to be extracted = fossil.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 FOSSIL mean?
FOSSIL noun- The mineralized remains of an animal or plant.
- Any preserved evidence of ancient life, including shells, imprints, burrows, coprolites, and organically-produced chemicals.
- A fossil word.
- Anything extremely old, extinct, or outdated.