Merge rasters and clip by a shapefile

Question

I was wondering how to merge multiple TIFF files together and clip the mosaic by the bounds of a intersecting shapefile. I've been able to merge them and output as a .tiff, but am not sure how to to mask the mosaic before outputting.

import os 
import rasterio 
from rasterio.merge import merge

tiffs_path = ['my_file1','my_file2' ]

shape_path = 'my_shape'

raster_to_mosaic = []
for x in tiffs_path:
    raster = rasterio.open(x)
    raster_to_mosaic.append(raster)

mosaic, output = merge(raster_to_mosaic)

output_meta = raster.meta.copy()
output_meta.update({
        'driver' :'GTiff',
        'height': mosaic.shape[1],
        'width': mosaic.shape[2],
        'crs':'EPSG:4326',
        'compress':'lzw',
        'transform': output
        })

with rasterio.open('merged_raster.tiff', 'w+', **output_meta) as m:
        m.write(mosaic)