The most common and most likely answer to this crossword clue is the 8 letter word GEODESIC
I've seen this crossword clue in The Times
G
E
O
D
E
S
I
C
Buddy explains!
The straight part
We know that "type of survey" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case type of survey = geodesic.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 GEODESIC mean?
GEODESIC noun- The shortest line between two points on a specific surface.
- (spherical geometry) A segment of a great circle.
- A course allowing the parallel-transport of vectors along a course that causes tangent vectors to remain tangent vectors throughout that course (a straight curve, a line that is straight).
- Of or relating to geodesy.
- Of or relating to a geodesic dome.