A lot must be upset about management buyout being a lottery (7)
I believe the answer is:
tombola
'a lottery' is the definition.
(tombola is a kind of lottery)
'a lot must be upset about management buyout' is the wordplay.
'must be upset' is an anagram indicator.
'about' indicates putting letters inside.
'management buyout' becomes 'mbo' (abbreviation for management buyout).
'a'+'lot'='alot'
'alot' with letters rearranged gives 'tola'.
'tola' enclosing 'mbo' is 'TOMBOLA'.
'being' is the link.
(Other definitions for tombola that I've seen before include "fund-raising event" , "Tickets are drawn from a revolving drum in this raffle" , "Rotating drum game" , "Game with tickets drawn from a revolving drum" , "gambling activity" .)