Calls for problems around start of the week (7)
I believe the answer is:
summons
'calls for' is the definition.
('summon' can be a synonym of 'call for')
'problems around start of the week' is the wordplay.
'problems' becomes 'sums' (arithmetic problems).
'around' is an insertion indicator.
'start of the week' becomes 'mon' (Monday).
'sums' placed around 'mon' is 'SUMMONS'.
(Other definitions for summons that I've seen before include "Call (to court)" , "Calls to appear" , "Call to join" , "Subpoena" , "Order to appear in law court" .)