Possible Clues:

• Be of __: aid
• Of ___ (availing)
• "... breathe such vows as lovers --- swear" (Shak.)
• Is of -- (benefits)
• Be of __ (aid)
• Be of ___
• Be of __ (help)
• Of ___ (helping)
• Of ___ (servicing)
• Be of ___ (assist)