Idea I introduced in local office - crazy, but not initially (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')
'i introduced in local office crazy but not initially' is the wordplay.
'introduced in' indicates putting letters inside.
'local office' becomes 'branch' (I've seen this before).
'crazy' becomes 'wild' (I've seen this in another clue).
'but not initially' means to remove the first letter.
'wild' with its initial letter taken off is 'ild'.
'branch'+'ild'='branchild'
'i' inserted inside 'branchild' is 'BRAINCHILD'.
(Other definitions for brainchild that I've seen before include "Invention" , "wheeze" , "Bright idea" , "Original idea or work" , "One's original idea" .)