The most common and most likely answer to this crossword clue is the 11 letter word TENTERHOOKS
I've seen this crossword clue in The Guardian
T
E
N
T
E
R
H
O
O
K
S
More clues leading to the result TENTERHOOKS
Buddy explains!
The straight part
We know that "on which you wait nervously" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case on which you wait nervously = tenterhooks.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 TENTERHOOKS mean?
TENTERHOOKS noun- One of a series of hooks used to stretch cloth on a tenter.