NORTH  A72  A732  T3  KQJ7  Q4  KQ865  Q7652  5    T  JT94  A4  AT6432    KJ98653    KJ98  98

Dealer: South    Vul: None   MP Scoring West Pass Pass North 4 East Pass South 3 Pass

West the singleton 5 won by East's A.
Only one club remained outstanding, the 8.
East returned lowest club, the 2, requesting the lowest ranking suit of diamonds and hearts.

West dutifully returned the 5 to East's A.

What should East return? Shouldn't it be a club for West to overruff?

East decided that the 5 was an original 4th best, promising, after this auction, the remaining top diamond honour, the K.

If declarer had originally held KJ98653 K J98 98, East would have to return a diamond, since declarer could otherwise ruff a club with the K, cash the , win A and discard two losing diamonds on the A and Q.

East suggested it better for West to return an original 4th best diamond only to promise the top K and no interest in a club ruff.
Returning the top diamond spot card 7 should tend to deny interest in a club ruff (or attempt).