Related Clues:

• Do basic math
• Also mention
• Lack of focus, colloquially
• Word near the bottom of a dipstick
• Reckon on a clergyman joining
• Tot worrying Dad
• Put together - append
• Put together — attach
• Find 9-Across
• Hook up with, on Facebook?
• Combine numbers
• Mix (in)
• Build on, with 'to'
• Do some sums
• Tack on a few extra