Annual large staff bill is after tax essentially (7)
I believe the answer is:
almanac
'annual' is the definition.
(I know that almanac is a type of annual)
'large staff bill is after tax essentially' is the wordplay.
'large' becomes 'L' (eg in clothes sizes).
'staff' becomes 'man' (as in staffing or manning a particular place).
'bill' becomes 'ac' (short for account).
'is after' means one lot of letters go next to another.
'essentially' says to take the centre.
The centre of 'tax' is 'a'.
'l'+'man'+'ac'='lmanac'
'lmanac' put after 'a' is 'ALMANAC'.
(Other definitions for almanac that I've seen before include "Informative calendar" , "Annual publication giving dates of astronomical and other events" , "Year book with astronomical events, tides etc" , "Yearly publication with calendar etc" , "Sailor's or farmer's calendar" .)