A CLRNC MISINTERP CAUSES AN ALT EXCURSION IN THE PHX; AZ; CLASS B AIRSPACE.

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OUR FLT WAS AT THE ARLIN INTXN ON THE ARLIN 2 ARR TO PHX. THE CTLR ISSUED A VECTOR OF HDG 050 DEGS; INTERCEPT THE PHX 057 DEG RADIAL; DSND AND MAINTAIN 8000 FT. I READ BACK 'ACR XXX; 050 DEGS; TRACK INBOUND ON THE PHX 057 DEG RADIAL 7000 FT;' AT WHICH TIME 7000 FT WAS SET IN THE ALT ALERT WINDOW ON THE MCP. NO CORRECTION WAS MADE BY PHX APCH CTL AS TO MY INCORRECT ALT READBACK. WHILE PASSING APPROX 7500 FT; PHX APCH CTL ISSUED A CLB CLRNC BACK TO 8000 FT AND TO WATCH FOR TFC AT 7000 FT NWBOUND. ACR XXX ASSUMED AN IMMEDIATE CLB LEVELING OFF AT 8000 FT. ACFT SEPARATION WAS NOT COMPROMISED. THERE WAS A LOT OF RADIO CHATTER. I FEEL THE COMBINATION OF HDG; RADIAL INTERCEPTION AND ALT CHANGE INFO GIVEN ALL AT ONCE; COMBINED WITH THE BUSY PHX TCA AND RADIO CHATTER CONTRIBUTED TO THE 'MIS-SPEAK' AND 'MIS-DIAL' OF ALT OF 7000 FT; AND MAY HAVE LED TO A POSSIBLE VIOLATION OF ACFT ALT. ALSO; THE LAST DAY OF 4 AND AN 11-12 HR DAY (AWAKE) MAY HAVE CONTRIBUTED TO THE DEV (FATIGUE). SUPPLEMENTAL INFO FROM ACN 494710: I CALLED APCH CTL AFTER LNDG AND THEY STATED THEY HAD LISTENED TO THE TAPE AND WE HAD BEEN CLRED ONLY TO 8000 FT AND THAT WE HAD READ BACK 8000 FT.