My thanks to Colleague for an enjoyable solve.  My final grid looked like this:

Before I had solved 28d’s $BIRD, the Title took me longer to decipher than perhaps it should. I had replaced 41, 6 & 10 with their clue answers at first, leading to “ONE TIMOTHY UNFORTUNATE: STERN”.  I then tried to make sense of that perhaps reading ONE+TIM+(unfortunate)E. Was there a ONE-TIME PAD involved, somehow?  ‘DELTA’ in Row 13 looked possibly interesting (relevant), too.

I then spotted CENT.SIMO and decided it was a coin.  I did then briefly check to see if these had all been square coins – or coins with square holes in them – but couldn’t convince myself that either of these were true.  Nonetheless my highlighting gives square results.

I liked how ‘MONEY’ being the root of all coins resolved the ambiguity with DANDIPRAT / DANDYPRAT – that was a nice touch.  And 5a’s use of ‘toffy’ = U was something I hadn’t seen before and worked well in that clue.

My thanks again to Colleague!

Cheers & stay safe,

Tim(othy) / Encota