How to add shadow to ClipOval in flutter?

You can create your own CustomClipper

class CustomClipperOval extends CustomClipper<Rect> {
  @override
  Rect getClip(Size size) {
    return Rect.fromCircle(
        center: new Offset(size.width / 2, size.width / 2),
        radius: size.width / 2 + 3);
  }

  @override
  bool shouldReclip(CustomClipper<Rect> oldClipper) {
    return false;
  }
}

class ClipOvalShadow extends StatelessWidget {
  final Shadow shadow;
  final CustomClipper<Rect> clipper;
  final Widget child;

  ClipOvalShadow({
    @required this.shadow,
    @required this.clipper,
    @required this.child,
  });

  @override
  Widget build(BuildContext context) {
    return CustomPaint(
      painter: _ClipOvalShadowPainter(
        clipper: this.clipper,
        shadow: this.shadow,
      ),
      child: ClipRect(child: child, clipper: this.clipper),
    );
  }
}

class _ClipOvalShadowPainter extends CustomPainter {
  final Shadow shadow;
  final CustomClipper<Rect> clipper;

  _ClipOvalShadowPainter({@required this.shadow, @required this.clipper});

  @override
  void paint(Canvas canvas, Size size) {
    var paint = shadow.toPaint();
    var clipRect = clipper.getClip(size).shift(Offset(0, 0));
    canvas.drawOval(clipRect, paint);
  }

  @override
  bool shouldRepaint(CustomPainter oldDelegate) {
    return true;
  }
}

And then to use it

ClipOvalShadow(
  shadow: Shadow(
    color: Colors.amber,
    offset: Offset(1.0, 1.0),
    blurRadius: 2,
  ),
  clipper: CustomClipperOval(),
  child: ClipOval(
    child: Material(
      color: Colors.white, // button color
      child: InkWell(
        // splashColor: Colors.red, // inkwell color
        child: Container(
          width: 46,
          height: 46,
          child: Icon(
            Icons.menu,
            color: Colors.black,
          ),
        ),
        onTap: () {},
      ),
    ),
  ),
),

The Result will be

Adding shadow to ClipOval:

Center(
          child: Container(
            decoration: BoxDecoration(
              shape: BoxShape.circle,
              boxShadow: [
                BoxShadow(
                  color: Colors.green,
                  blurRadius: 50.0,
                  spreadRadius: 10.0,
                )
              ],
            ),
            child: ClipOval(
              child: Image.network(
                'https://i.picsum.photos/id/384/536/354.jpg?hmac=MCKw0mm4RrI3IrF4QicN8divENQ0QthnQp9PVjCGblo',
                width: 100,
                height: 100,
                fit: BoxFit.cover,
              ),
            ),
          ),
        ),

Output: