Trouble at the optical centre? (3)
I believe the answer is:
tic
'trouble' is the definition.
The answer and definition can be both states of affairs as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'at the optical centre?' is the wordplay.
'centre?' indicates the answer is hidden within the clue (hidden in the middle of the letters).
'TIC' can be found hidden inside 'at optical'.
Can you help me to learn more?
(Other definitions for tic that I've seen before include "Spasmodic muscular twitch" , "Jerky movement" , "Facial movement" , "Nervous response" , "Nervous twitch" .)