The most common and most likely answer to this crossword clue is the 7 letter word OUTCROP
I've seen this crossword clue in The Times
O
U
T
C
R
O
P
More clues leading to the result OUTCROP
- Maybe harvest more than in rocky spot
- Yield more than rock
- To produce a larger harvest, perhaps, a sudden occurrence
- Flowering potatoes, say, to appear out of the earth
- Spur to win in hairdressing contest!?
- Work on criminal court appearance
- Rocky appearance of dated hairstyle
- Rock formation exposed by harvest
- Produce more veg than what pokes out of the ground
- Broadcast cut poor rock
Buddy explains!

The straight part
We know that "rock" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rock = outcrop.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 OUTCROP mean?
OUTCROP noun- A piece of land that stands out (usually into water) from the land surrounding.
- A coming out of bedrock or of an unconsolidated deposit to the surface of the ground.
- The part of a rock formation that appears at the surface of the ground.
- (of a stratum) To come out to the surface of the ground.