Discharge university dons beginning to expect time off (10)

'discharge' is the definition.
(I know that evacuation is a type of discharge)

'university dons beginning to expect time off' is the wordplay.
'university' becomes 'u' (abbreviation for university).
'dons' indicates putting letters inside (don means to wear or put on).
'beginning to' says to take the initial letters.
'time off' becomes 'vacation' (vacation is a kind of time off).
The initial letter of 'expect' is 'e'.
'e'+'vacation'='evacation'
'u' going within 'evacation' is 'EVACUATION'.