Yes, there is. I didn’t think so until a few minutes ago, nothing worked, but here you go:
Trim Footage + Trim Comp to Work Area + Drag into main comp + Time Remapping + a loop expression
1) Drag your footage onto the “Create a new Composition” button.
2) In the new comp, trim the footage, I double clicked the layer and set new in and out points with the “Set New In Point at Current Time” button (and outpoint too).
3) The In point (where you made the cut) of the trimmed layer should have slide over to time 0. Now, “O” on the keyboard puts the time Indicator at the new out point, and “N” set the end of the work area. Then, Composition>Trim Comp to Work Area, shortens the comp so the trimmed footage fills it.
4) Drag your Trimmed Footage Comp into the longer comp where you want it to loop.
5) Select the layer and Layer>Enable Time Remapping.
6) Alt Click the Time Remapping Stopwatch and paste this loop expression into the expression field:
loopOut(“cycle”, 0)
7) Now drag the end point of the layer out as far as you want it to loop.