Worry as new gaffer sets tasks at the outset (5)
I believe the answer is:
angst
'worry' is the definition.
(I've seen this before)
'as new gaffer sets tasks at the outset' is the wordplay.
'at the outset' says to take the initial letters (the outset is the beginning).
The initial letters of 'as new gaffer sets tasks' is 'ANGST'.
(Other definitions for angst that I've seen before include "Acute but unspecified feeling of worry" , "Extreme anxiety" , "Profound feeling of anxiety or dread" , "uneasiness" , "Nagging worry" .)