Clue: Staff officer with small house in London area (4)
Answer: SOHO
Explanation: Definition: London area
A charade of SO ('Staff Officer') plus HO ('small house'). Also an area of Manhattan, named not after the London area (although that might have been involved to some extent), but because it is south of Houston Street (which is pronounced how-ston, being named after a different fellow from the Sam Houston after whom the Texas city is named).