For a particular purpose only (2,3)
I believe the answer is:
ad hoc
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">for a particular purpose only</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for ad hoc that I've seen before include "(Of group) formed for one purpose only" , "For a specific purpose - Latin expression" , "For a specific purpose, say an arrangement" , "specific occasion" , "(Of committee) formed for a single purpose" .)