The most common and most likely answer to this crossword clue is the 7 letter word COMPILE
I've seen this crossword clue in The Daily Telegraph
C
O
M
P
I
L
E
More clues leading to the result COMPILE
Buddy explains!

The straight part
We know that "Gather" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case gather = compile.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 COMPILE mean?
COMPILE noun- An act of compiling code.
- To put together; to assemble; to make by gathering things from various sources.
- To construct, build.
- To use a compiler to process source code and produce executable code.
- To be successfully processed by a compiler into executable code.
- To contain or comprise.
- To write; to compose.