Rolling stone's lack (4)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">rolling stone's lack</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for moss that I've seen before include "evidence of neglect?" , "Plant growing on many lawns" , "Green-carpet plant" , "Plant(s) not wanted on lawns" , "Type of plant growing in damp places" .)