Signs midday's about time when lunch is taken? (8)
I believe the answer is:
notation
'signs' is the definition.
(thesaurus)
'midday's about time when lunch is taken?' is the wordplay.
'midday' becomes 'noon' (synonyms).
'about' indicates putting letters inside.
'time' becomes 't' (abbreviation).
'when lunch is taken?' becomes 'atI' (resembles 'at 1' as in 1pm).
't'+'ati'='tati'
'noon' placed around 'tati' is 'NOTATION'.
(Other definitions for notation that I've seen before include "A comment added to a text" , "Written comment" , "System of written symbols representing something" , "Set of representative symbols" , "Set of symbols representing quantity etc." .)