### Clue: Part of a log where prayer sat endlessly (8)
### Answer: MANTISSA 
 ### Explanation: Definition: Part of a log
[Praying] MANTIS + SA[t]. When I was doing my A-levels in the days before cheap calculators, we used logs (logarithms) to multiply and divide numbers. These were divided into the Characteristic before the decimal point and the MANTISSA after it.