Foolishly pester one during the break (7)
I believe the answer is:
respite
'the break' is the definition.
('respite' can be a synonym of 'break')
'foolishly pester one during' is the wordplay.
'foolishly' is an anagram indicator.
'one' becomes 'i' (Roman numeral).
'during' means one lot of letters goes inside another.
'pester' anagrammed gives 'respte'.
'respte' enclosing 'i' is 'RESPITE'.
(Other definitions for respite that I've seen before include "Pause to rest" , "Pause from exertion, etc" , "temporary delay" , "Pause; reprieve" , "See trip (anag.)" .)