Granting webservd permission to just write to (not read from) a single file (mode 640) on a directory owned by bob. Note that according to the initial setup, by "other" permission bit, webservd wouldn't be able to write to any file at all.
bob@box-01:~/dir1 $ printf "Hello" > file2
bob@box-01:~/dir1 $ chmod 640 file2
bob@box-01:~/dir1 $ ll -dV file2
-rw-r----- 1 bob staff 5 Jun 20 10:12 file2
owner@:rw-p--aARWcCos:-------:allow
group@:r-----a-R-c--s:-------:allow
everyone@:------a-R-c--s:-------:allow
bob@box-01:~/dir1 $ chmod A+user:webservd:waRcs:allow file2
bob@box-01:~/dir1 $ ll -dV file2
-rw-r-----+ 1 bob staff 5 Jun 20 10:12 file2
user:webservd:-w----a-R-c--s:-------:allow
owner@:rw-p--aARWcCos:-------:allow
group@:r-----a-R-c--s:-------:allow
everyone@:------a-R-c--s:-------:allow
webservd@box-01:/home/bob/dir1 $ cat file2
cat: cannot open file2: Permission denied
webservd@box-01:/home/bob/dir1 $ echo ', world!' >> file2
webservd@box-01:/home/bob/dir1 $ ll file2
-rw-r-----+ 1 bob staff 14 Jun 20 10:15 file2
bob@box-01:~/dir1 $ cat file2
Hello, world!
webservd@box-01:/home/bob/dir1 $ rm file2
rm: file2 not removed: Permission denied
