The most common and most likely answer to this crossword clue is the 5 letter word FRILL
I've seen this crossword clue in Financial Times
F
R
I
L
L
More clues leading to the result FRILL
- Ruffle little stream after opening of fishing
- Gathering to occupy both sides of river
- Father badly ruffled strip of cloth
- Luxury end of Gulf Stream
- Gathering stuff about king or queen
- … brother’s not feeling well — in fact rough, you might say!
- Cockneys’ excitement seeing gathering
- Leader of regime in charge, one’s gathered
- Decorative touch makes French sick
- Ruffle feathers initially next to small brook
Buddy explains!

The straight part
We know that "Gathering" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case gathering = frill.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 FRILL mean?
FRILL noun- A strip of pleated fabric or paper used as decoration or trim.
- A substance or material on the edge of something, resembling such a strip of fabric.
- A wrinkled edge to a film.
- Something extraneous or not essential; something purely for show or effect; a luxury.
- The relatively extensive margin seen on the back of the heads of reptiles, with either a bony support or a cartilaginous one.
- To make into a frill.
- To become wrinkled.
- To provide or decorate with a frill or frills; to turn back in crimped plaits.
- To shake or shiver as with cold (with reference to a hawk).
- To cry (with reference to a bird of prey).