<a id="idIndexMarker-616"></a> is a dummy element, the "id" that works as anchor can be anywhere else. It is indeed more semantic to use it as an empty anchor point than using e.g. a <span>, but as you see, it's not always possible to use it.
I would write:
Code:
see “<a href="e_7_ch1-2.xhtml#Anchor-2"><span id="idIndexMarker-616">Exercise 1.13</span>. Moon Meditation (Figure 1.5)</a>”
(quotes outside the link, and index-span containing the indexed term, which is presumably "Exercise 1.13")