Literally, "I can work with that" referring to the attractiveness of the subject being discussed. Typically someone who is ICWWT is not the first choice, but depending on circumstances they may be good enough, or all that the person saying it can hope to get.
See also work hot
Mary: What do you think about Bob?
Susan: He's not the hunk I hoped for, but I am looking to settle down, and as far as spending the rest of my life with a guy, I guess he's ICWWT.