Peter’s wrong about the lunchtime break (7)
I believe the answer is:
respite
'break' is the definition.
(I know that respite is a type of break)
'peter's wrong about the lunchtime' is the wordplay.
'wrong' indicates an anagram.
'about' indicates putting letters inside.
'the lunchtime' becomes 'I' (one o'clock is I on a clock with Roman numerals).
'peters' is an anagram of 'respte'.
'respte' placed around 'i' is 'RESPITE'.
(Other definitions for respite that I've seen before include "Relief; breather" , "See trip (anag.)" , "Short period of relief" , "Period of relief (from unpleasant thing)" , "temporary delay" .)