The most common and most likely answer to this crossword clue is the 11 letter word BUTTERFLIES
I've seen this crossword clue in The Daily Telegraph
B
U
T
T
E
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F
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S
More clues leading to the result BUTTERFLIES
- Races after ram maybe in a state of nervousness
- Monarchs, for example, creating feeling of anxiety
- Nervous feeling spread over device in trousers
- Goat runs away from insects
- British are mendacious about female monarchs, say
- Hill right beside terminal in Banff deceives some travellers by air
- Sign of nerves as goat moves quickly
Buddy explains!

The straight part
We know that "Sign of nerves" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sign of nerves = butterflies.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 BUTTERFLIES mean?
BUTTERFLIES noun- (by ellipsis) butterflies in one's stomach
- A flying insect of the order Lepidoptera, distinguished from moths by their diurnal activity and generally brighter colouring.
- A use of surgical tape, cut into thin strips and placed across an open wound to hold it closed.
- The butterfly stroke.
- (in plural) A sensation of excited anxiety felt in the stomach.
- Someone seen as being unserious and (originally) dressed gaudily; someone flighty and unreliable.
- To cut (food) almost entirely in half and spread the halves apart, in a shape suggesting the wings of a butterfly.
- To cut strips of surgical tape or plasters into thin strips, and place across (a gaping wound) to close it.