Idea from one in local office’s killed regularly (10)
I believe the answer is:
brainchild
'idea' is the definition.
(I have seen 'Bright idea' mean 'brainchild' so perhaps 'idea' could also mean 'brainchild')
'one in local office's killed regularly' is the wordplay.
'one' becomes 'I' (Roman numeral).
'in' is an insertion indicator.
'local office' becomes 'branch' (I've seen this before).
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
The alternating letters of 'killed' are 'ild'.
'i' going within 'branch' is 'brainch'.
'brainch'+'ild'='BRAINCHILD'
'from' is the link.
(Other definitions for brainchild that I've seen before include "Original idea or work" , "wheeze" , "One's original idea" , "Invention" , "Bright idea" .)