Unifying ideas or motifs (6)
I believe the answer is:
themes
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">unifying ideas</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >'<span class="explanation-format__original">motifs</span>' is the second definition.<br/ ><span class="explanation-format__explanation">('theme' can be a synonym of 'motif')</span><br/ ><br/ ></span>
(Other definitions for themes that I've seen before include "Topics, ideas, motifs" , "'Subjects, topics (6)'" , "items proposed for discussion" , "Subjects or repeated musical pieces" , "Motifs, subjects" .)