KLEMENTYNA: Look at all those books and magazines and other things all over the floor! You should really clean your room!
FRED: But it is clean. Do you mean tidy my room?
We are being a bit picky here so I apologise for that. (Picky means that I complain about very small things which, to be honest, just aren’t worth complaining about.)
In Polish – and here, I really do suspect that this is in a lot of other languages too – often one word is enough to describe the activity of cleaning a room (removing dirt) and tidying a room (making it neat by putting things back into their proper places). Clean up, however, could be interpreted in both ways in English as it means ‘clean and tidy’, although this is usually as a result of being dirty first.
To be honest, I’ve heard the odd native speaker use ‘clean’ when they mean ‘tidy’ to refer to a mess of things in a place such as papers and books which don’t usually leave dirt (unless you’re clearing out an old room or dusty attic). Such a state can look not very pleasant, and something that doesn’t look pleasant could be interpreted as a kind of ‘dirt’.
If we had to choose precise language for Klementyna, than I would tell Fred to tidy his room. If there’s a lot of things that are not dirty or are not going to leave dirty marks but need to be disposed, then I would tell him to clear his room.
But as I say, I’m being picky here. So if you want to get it right, use the right verb; if not, well, I know what you mean.
It’s a bit like eat lunch and have lunch. Who really worries?