The most common and most likely answer to this crossword clue is the 10 letter word PROCTOLOGY
I've seen this crossword clue in The Guardian
P
R
O
C
T
O
L
O
G
Y
Buddy explains!
The straight part
We know that "Looking up passages" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case looking up passages = proctology.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 PROCTOLOGY mean?
PROCTOLOGY noun- The branch of medicine dealing with the pathology and surgery of the colon, rectum, and anus.
- Colorectal surgery as a specialty inside proctology.