… perhaps, holding nothing is gloomy (6)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

I was all set to chunter [again] about meaningless ellipses but these dots are not an ellipsis – they’re MORSE code, into which we have to put O [nothing]: I can’t see any significance in them standing for S S  but that doesn’t mean there isn’t any.