ogr2ogr -overwrite -update -clipsrc clip_shape.shp PG:"host=subsethost user=subsetloginname dbname=subsetdb password=subsetpassword" PG:"host=originalhost user=originalloginname dbname=originaldb password=originalpassword"

COPY { table_name [ ( column_name [, ...] ) ] | ( query ) }
    TO { 'filename' | PROGRAM 'command' | STDOUT }
    [ [ WITH ] ( option [, ...] ) ]

COPY ( SELECT * FROM tbl WHERE ST_Intersects(myextent, tbl.geom) ) TO 'foo.csv' WITH ( format csv )