Undertakings question case for tortuous checks (5)
I believe the answer is:
tasks
'undertakings' is the definition.
('task' can be a synonym of 'undertaking')
'question case for tortuous checks' is the wordplay.
'question' becomes 'ask' (asking a question).
'case for' means to remove the middle letters (the letters which encase the others are used).
'checks' indicates putting letters inside (inserted letters are checked or controlled).
'tortuous' with its centre taken out is 'ts'.
'ask' going inside 'ts' is 'TASKS'.
(Other definitions for tasks that I've seen before include "Pieces of work" , "Jobs to be done" , "Assignments" , "charges" , "Chores, jobs" .)