Young radio AGN are pivotal for our understanding of many of the still-debated aspects of AGN feedback .
In this paper we present a study of the interstellar medium ( ISM ) in the compact , peaked-spectrum radio galaxy PKS B1934-63 using X-shooter observations .
Most of the warm ionized gas resides within a circum-nuclear disk with a radius of about 200 pc that is likely to constitute the gas reservoir from which the central black hole feeds .
On the other hand , we find a biconical outflow of warm ionized gas with an estimated radius of 59 \pm 12 pc .
This matches the radial extent of the radio source and suggests that the outflow is jet driven .
Thanks to the superior wavelength coverage of the data , we can estimate the density of the warm ionized gas using the trans-auroral line technique , and we find that the outflowing gas has remarkably high density , up to \log n _ { e } ~ { } ( { cm ^ { -3 } } ) \simeq 5.5 .
The estimated mass outflow rate is low ( \dot { M } = 10 ^ { -3 } -10 ^ { -1 } ~ { } { M _ { \odot } ~ { } yr ^ { -1 } } ) , and the AGN feedback operates at relatively low efficiency ( \dot { E } / L _ { bol } \sim 10 ^ { -4 } - 10 ^ { -3 } \% ) .
In addition , optical and near-IR line ratios show that the expansion of the radio source drives fast shocks ( with velocities v _ { s } \gtrsim 500 km s ^ { -1 } ) that ionize and accelerate the outflowing gas .

At odds with the properties of other compact , peaked-spectrum radio sources hosting warm ionized gas outflows , we do not find signs of kinematically disturbed or outflowing gas in phases colder than the warm ionized gas .
We argue that this is due to the young age of our source and thus to the recent nature of the AGN-ISM interaction , and suggest that cold gas forms within the outflowing material and the shock-ionized outflowing gas of PKS B1934-63 did not have enough time to cool down and accumulate in a colder phase .
This scenario is also supported by the multi-phase outflows of other compact and young radio sources in the literature .