Eliminate combinations
Every combination in the list has the correct sum and distinct digits. But whole combinations can still be ruled out: a digit already present in the cage's row cannot be used in any of its cells. Click combinations to eliminate them, just as in the game's Killer tools.
Worked example
A two-cell cage with total 5 has combinations 1 + 4 and 2 + 3. If both cage cells are in a row that already contains 4, rule out 1 + 4, leaving 2 + 3.