Fit for purpose (6)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">fit for purpose</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 usable that I've seen before include "(Of, eg, tool) employable" , "exploited" , "Functional, handy" , "open to exploitation" , "not to be discarded?" .)
(Other definitions for proper that I've seen before include "Actual" , "Seemly" , "Appropiate, right" , "Appropriate according to rules" , "well-behaved" .)
(Other definitions for useful that I've seen before include "Functional, handy" , "Of service" , "Advantageous, serviceable" , "Capable of serving some purpose" , "Expedient" .)