### Clue: In the morning, grunts lifting up letter (5)
### Answer: SIGMA 
 ### Explanation: Definition: letter
 **Reversal of**(… lifting up, in a down clue) [AM(abbrev. for "ante meridiem"/in the morning, before noon, hours of the day) + GIS(plural of GI/American solders/grunts)].
Defn: … in the Greek alphabet.