### Clue: PM once ignoring head of Treasury to protect Welsh woman and foreign nationals? (8)
### Answer: RUSSIANS 
 ### Explanation: Definition: foreign nationals
An envelope ('to protect') of SIAN ('Welsh woman') in [t]RUSS (Mary Elizabeth, or Liz, 'PM once' – or did you blink?) minus the T ('ignoring head of **T**reasury')