Leave boy with daughter, hiding in the grass (4-3)

'leave' is the definition.
(leave is time off work)

'boy with daughter hiding in the grass' is the wordplay.
'boy' becomes 'alf' (I've seen this before**).
'with' says to put letters next to each other.
'daughter' becomes 'd'.
'hiding in' indicates putting letters inside.
'the grass' becomes 'hay' (I have seen 'Mown grass ' mean 'hay' so perhaps 'grass' could also mean 'hay').
'alf'+'d'='alfd'
'alfd' going into 'hay' is 'HALF-DAY'.