If that's the PCV hose, without it will cause excessive crank case pressures and it will result in oil coming out of the easiest exit. Sometimes its the dipstick tube other times its the rear main seal, or valve cover gasket. I would get it fixed ASAP.
'87 YJ, 4.2L built and bored, 8" of lift, 8.8 rear, AX15/NP 231J, Tom Woods drive shafts, Flat fenders, 12,000LB winch, Custom bumpers, Rattle can paint job. Never completed...