An exterior mirror assembly for a vehicle includes a mounting portion mountable at a side of a vehicle, a mirror head portion at the mounting portion, and an actuator. The mirror head portion includes a mirror casing and a reflective element at least partially housed at the mirror casing. The actuator is operable to impart pivotal movement of the reflective element mirror relative to the mirror casing to adjust a rearward field of view of a driver of the vehicle. The actuator includes a drive post that is pivotally attached at the reflective element. The actuator also includes a motor that rotatably drives a clutch device to adjust the drive post to adjust the reflective element relative to the mirror casing. The clutch device allows for manual adjustment of the reflective element and the drive post in a non-ratcheting manner.