Old-time oath (4)
I believe the answer is:
egad
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">old-time oath</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for egad that I've seen before include "My word once" , "Oath sworn" , "Old oath" , "Old exclamation; aged (anagram)" , "Christ" .)