importprivkey (insert private key here without brackets)
hit enter and wait a while for the funds to be found on the blockchain.
You can then use "coin control" to either sweep them to a new wallet address, or, spend in increments.
Since only few people bother to use Bitcoin Core as wallet these days, it's longer than most of you think. In my case, it took almost an hour (i use HDD) after hit "Enter".
P.S. in future waiting time might be reduced to few seconds if feature called "Address Index" is added to Bitcoin Core.