Employ a layabout? Only partly true (5)
I believe the answer is:
loyal
'true' is the definition.
(I've seen this before)
'employ a layabout? only partly' is the wordplay.
'only partly' says the answer is hidden in the clue.
'LOYAL' is hidden within 'employ a layabout'.
(Other definitions for loyal that I've seen before include "Showing firm allegiance" , "Staunch" , "Dedicated" , "Unwaveringly devoted to friend or cause" , "Faithful - true" .)