The clip CSS property is deprecated, clip-path should be used instead, although it is still tagged as experimental (clip-path) not being compatible with all browsers. I think it would be better to use a workaround.
Did you add it to fix the missing for attribute in some <label> elements? If so I provided you with a possible solution in this thread.
I found the mentioned clip property in /css/styles.css:
/* For screen readers */
.iphorm-screen-reader-text {
clip: rect(1px, 1px, 1px, 1px);
height: 1px;
overflow: hidden;
position: absolute !important;
width: 1px;
word-wrap: normal !important; /* Many screen reader and browser combinations announce broken words as they would appear visually. */
min-height: 0 !important; /* Reset Quform style */
}