Adjusting (8)
(Other definitions for altering that I've seen before include "revising" , "Changing -- 1 across (anag)" , "making a change" , "Modifying, changing" , "Making changes" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">adjusting</span>' is the definition.<br/ ><span class="explanation-format__explanation">(attuning is a kind of adjusting)</span><br/ ><br/ >This is all the clue.<br/ ></span>