The most common and most likely answer to this crossword clue is the 8 letter word LANDFALL
L
A
N
D
F
A
L
L
More clues leading to the result LANDFALL
Buddy explains!

The straight part
We know that "reaching terra firma" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case reaching terra firma = landfall.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 LANDFALL mean?
LANDFALL noun- Arrival at the shore by ship.
- The point at which a hurricane or similar storm reaches land.
- The first land discovered after a sea voyage.
- A landslip.