The most common and most likely answer to this crossword clue is the 3 letter word TAT
I've seen this crossword clue in The Guardian
T
A
T
More clues leading to the result TAT
- Volunteers time to make knotted lace
- Make lace: stuff of poor quality
- Junk that is ignored by husband
- Rubbish skin pic
- Rubbish concealed by statistics
- Shabby stuff that may be returned unaltered
- Rubbish piece of needlework?
- Shoddy stuff that he initially rejected
- Rubbish article in Times
- After stripping, say things that are pretty seedy
Buddy explains!

The straight part
We know that "Rubbish" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rubbish = tat.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does TAT mean?
TAT noun- Cheap and vulgar tastelessness; sleaze.
- Cheap, tasteless, useless goods; trinkets.
- Gunny cloth made from the fibre of the Corchorus olitorius (jute).
- To make (something by) tatting.
- A pony.
- A tattoo.
- To apply a tattoo.