The most common and most likely answer to this crossword clue is the 4 letter word PITH
I've seen this crossword clue in The Daily Telegraph
P
I
T
H
More clues leading to the result PITH
- Stone with hard core
- Essence of fruit stone hearts
- Spithead has berth for this core section
- Mine hard substance
- Central region about to be discounted in playing area
- Fruit stone with hard white inner layer
- Husband’s upset about weight
- It’s topping for those in the sun, a certain coast, outré
- Playing area abandoned by college? That’s nub of matter
- Substance that’s hard found at bottom of mine
Buddy explains!

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 PITH mean?
PITH noun- The soft, spongy substance in the center of the stems of many plants and trees.
- The spongy interior substance of a feather or horn.
- The spinal cord; the marrow.
- The albedo of a citrus fruit.
- The essential or vital part; force; energy; importance.
- Power, strength, might.
- To extract the pith from (a plant stem or tree).
- To kill (especially cattle or laboratory animals) by cutting or piercing the spinal cord.
- One divided by pi.
- The ordinal form of the number pi.