Possible Clues:

• Employ completely and beneficially
• Thoroughly employ in a handy way
• Begin to give us some fuel to some purpose
• Exercise quite profitably
• Don't give part-time employment, perhaps
• To produce a benefit, leave no remnants
• Don't be so wasteful, perhaps
• Exhaust, in a way that's beneficial
• In a beneficial manner
• Don't employ one only part-time, it seems