The most common and most likely answer to this crossword clue is the 7 letter word TRUMPET
I've seen this crossword clue in The Daily Telegraph
T
R
U
M
P
E
T
More clues leading to the result TRUMPET
- Mutter in agitation about parking for orchestra member
- Advertise cut of steak in Tweets regularly
- Herald eclipse, one a long way from earth?
- Proclaim bottom end of page in Times
- It has a bell end and gives pleasure if blown
- Take trick before east voided and boast
- Politician interrupting real time broadcast
- Behind blocking name of offensive broadcast
- Loud sound from bottom — what was offensive about it?
- Blast comes from behind offensive trousers
Buddy explains!

The straight part
We know that "Make a big thing of/brass instrument" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case make a big thing of/brass instrument = trumpet.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 TRUMPET mean?
TRUMPET noun- A musical instrument of the brass family, generally tuned to the key of B-flat; by extension, any type of lip-vibrated aerophone, most often valveless and not chromatic.
- Someone who plays the trumpet; a trumpeter.
- The cry of an elephant, or any similar loud cry.
- One who praises, or propagates praise, or is the instrument of propagating it.
- A funnel, or short flaring pipe, used as a guide or conductor, as for yarn in a knitting machine.
- A kind of traffic interchange involving at least one loop ramp connecting traffic either entering or leaving the terminating expressway with the far lanes of the continuous highway.
- A powerful reed stop in organs, having a trumpet-like sound.
- To sound loudly, be amplified
- To play the trumpet.
- Of an elephant, to make its cry.
- To give a loud cry like that of an elephant.
- To proclaim loudly; to promote enthusiastically