Hamper from head of department is benefit (12)
I believe the answer is:
disadvantage
'hamper' is the definition.
('disadvantage' can be a synonym of 'hamper')
'head of department is benefit' is the wordplay.
'head of' says to take the initial letters.
'benefit' becomes 'advantage' (I've seen this before).
The initial letter of 'department' is 'd'.
'd'+'is'+'advantage'='DISADVANTAGE'
'from' is the link.
(Other definitions for disadvantage that I've seen before include "Drawback" , "Handicap" , "Hindrance" , "Flaw -- weak point" , "Catch" .)