Referee revealed for Old Firm derby clash between Celtic and Rangers
Clancy most recently encountered the two Glasgow giants within a ten-day spell in October. First he officiated Rangers' 1-1 draw with Hearts at Tynecastle before being the referee for Celtic's 2-0 home win over St Mirren.
The match at Celtic Park on December 29 is set to be a massive fixture in the 2019/20 Ladbrokes Premiership title race.
Both teams are in action on Boxing Day. Rangers host Kilmarnock with Steven McLean as referee, while Celtic will have their trip to St Mirren officiated by Willie Collum.