Home manager Jim Jefferies had the hosts fired up from the off but any chance of an upset was killed off after 22 minutes when Aird put Ally McCoist's side ahead.
And Dunfermline's first defeat in nine games was confirmed with three goals after the interval as the Light Blues extended their lead over the Pars to 14 points with a game in hand.
Stripped of their 100 per cent record by a draw with Stranraer on Boxing Day, the Ibrox men made sure they resumed their canter towards the title with a much-improved display.
This was a Scottish Premiership fixture only two years ago but the financial collapses suffered by both clubs meant they now faced off in the third flight.
However, the Ibrox men's unbeaten start to the season already had them stick-on favourites to claim the automatic promotion slot to the Championship well before they arrived at East End Park packing an double-digit lead over their hosts and nearest challengers.
After sucking up some early Pars pressure, they hit the home team with a sucker punch as Aird was allowed to advance forward before burying a low 20-yard strike.
They then doubled their lead six minutes after the restart as Clark pinched Jon Daly's net-bound effort with a header from point-blank range.
And on 70 minutes, substitute Lewis Macleod showed a sublime weight of pass as he rolled in Law for the third before Crawford rattled home a fourth in stoppage time.
Rangers will face Airdrie on January 2 - the same day as Dunfermline tackle Stenhousemuir - before travelling to Ochilview to take on the Warriors themselves three days later to play a rearranged clash that could see them go 17 points clear.