Insects showing signs of nervousness (11)
I believe the answer is:
butterflies
This clue might be a double definition.
'insects' is the first definition.
(butterfly is a kind of insect)
'signs of nervousness' is the second definition.
'butterflies' can be an answer for 'nervousness' (I've seen this in another clue). I am not certain of the 'signs of' bit.
'showing' acts as a link.
Can you help me to learn more?
(Other definitions for butterflies that I've seen before include "coppers?" , "Skippers, for example" , "insects?" , "Painted ladies, for example" , "Nervous sensation" .)