1) Be very cordial to 2) Behave 3) Display excessive cordiality 4) Display of friendship 5) Hearty congratulation 6) Hearty greeting Found on https://www.crosswordclues.com/clue/backslap
verb display excessive cordiality (towards); `he is always backslapping his colleagues at staff meetings` Found on https://www.encyclo.co.uk/local/20974