NY Times Crossword
December 31, 2019
Evan Kalish

1. Currency unit replaced by the Euro
2. Likely to be found in a Japanese garden
3. Almost identical pair, figuratively
4. It flows through Northern Italy
5. Common New Year's resolution - - as hinted at by the answers, in order, of the first four clues.

Answers:

1. English pound
2. Koi pond
3. Two peas in a pod
4. River Po
5. Lose weight

Explanation:
POUND (unit of weight) loses one letter in each progressive clue answer:

POUND
POND
POD
PO