Fuss I disapprove of that detains colleague hours (8)
I believe the answer is:
ballyhoo
'fuss' is the definition.
(commotion or excitement)
'i disapprove of that detains colleague hours' is the wordplay.
'i disapprove of that' becomes 'boo' (expression of disapproval).
'detains' means one lot of letters goes inside another.
'colleague' becomes 'ally' (ally can mean a colleague or associate).
'hours' becomes 'h'.
'ally'+'h'='allyh'
'boo' enclosing 'allyh' is 'BALLYHOO'.
(Other definitions for ballyhoo that I've seen before include "Blatant advertising - a holy lob (anag)" , "song and dance" , "Noisy or sensational publicity, hype" , "fuss about nothing?" , "Fuss; noisy publicity" .)