dig it out deeper and glue in a new piece , re shape it and glass it.
Done it a lot and it works great
If you do a good job on the shaping of the piece of foam
you glued in ; it won't need any filler.
If you have any questions , ( Pm: Terrie ) he's probably, at least,
one of the most knowledgeable people on this forum , when it comes
to composites .