Gonefishing

4 clues
Country doctor's day-off sign
Rural "Out of the office" sign
To ace Oceanography, don't let the prof know you've __
Classic out-of-office sign ... or what this puzzle's author has done?
Similar answers:
Abolishing
Admonishing
Afishingterm
Agemakerfishing
Astonishing
Banishing
Blemishing
Desktoppublishing
Diminishing
Diminishingreturns
Disestablishing
Dishing
Dishingdirt
Dishingthedirt
Dishingup
Doavanishingact
Embellishing
Establishing
Finishing
Finishingcoat