### Clue: An optimist's explanation in support of God (8)
### Answer: PANGLOSS 
 ### Explanation: Definition: An optimist
 GLOSS(one of several types of explanation, eg. one in the margin of a manuscript, a verbal one, a deliberately misleading one, or as a short form for glossary) **placed below**(in support of, in a down clue) PAN(the Greek mythological God of the fields, woods, shepherds and flocks represented as half man and half goat, and playing the pipes).
Answer: From the optimist Dr. Pangloss, mentor to start with of the main character in Voltaire's satire, Candide. The good Dr's mantra was "all is for the best in the "