Management requiring a million invested in boom? (5)
I believe the answer is:
admin
'management' is the definition.
(I've seen this before)
'a million invested in boom?' is the wordplay.
'million' becomes 'm' (abbreviation).
'invested in' indicates putting letters inside.
'boom?' becomes 'din' ('din' can be a synonym of 'boom').
'm' put inside 'din' is 'dmin'.
'a'+'dmin'='ADMIN'
'requiring' is the link.
(Other definitions for admin that I've seen before include "Form-filling (abbr.)" , "those running the show" , "Clerical work (abbr.)" , "routine business" , "Business organisers" .)