You may see the following TimeQuest unconstrained clock when using the Arria® V device transceiver Custom PHY in Quartus® II software version 13.0 and later.
"*|altera_xcvr_custom:phy_inst|av_xcvr_custom_nr:A5|av_xcvr_custom_native:transceiver_core|av_xcvr_native:gen.av_xcvr_native_insts[0].gen_bonded_group.av_xcvr_native_inst|av_xcvr_avmm:inst_av_xcvr_avmm|avmm_interface_insts[0].av_hssi_avmm_interface_inst~BURIED_ASYNC_DATA_OUT"
It is safe to ignore this unconstrained clock in the Quartus II software.