You are South in 6S after uncontested bidding. West leads the DJ on which dummy plays low and you win with the DA. You then clear trumps in three rounds with West discarding the H3.
How do you plan to make your slam?
See Klinger's answer below.
"On the assumption that West is highly unlikely to lead a diamond from a KJT holding against a slam, there is a very good line after trumps behave. Continue with the CA, CK and CQ, discarding your losing diamond.
Continue with the fourth club. When the clubs are 4-3 and East has the fourth club, discard a heart and let East hold the trick. As the cards lie, East is endplayed and has to give you the twelfth trick in one red suit or the other. If East exits with a low diamond, you have to decide whether to play East for the DK or West for the HK.
If East shows out on the fourth club, you can ruff and play a heart to the queen. If this loses, East will still be endplayed if holding the DK and HJ. As it happens the HK is onside, but you should not be pinning all your hopes on that.
Tip: If a finesse is enough to give you your contract, try to use the finesse as a last resort. See if you can find a line of play which avoids the need for the finesse."
This hand and analysis comes from a Bridge Desk Calendar (from more than a decade ago) item written by Ron Klinger.