### Clue: Current head of school quits physics, say, about little cash at the beginning (10)
### Answer: INCIPIENCE 
 ### Explanation: Definition: the beginning
A charade of IN ('current') plus CIPIENCE, an envelope ('about') of IP (one P, 'little cash') in [s]CIENCE ('physics,say') minus the S ('head of **S**chool quits').