The most common and most likely answer to this crossword clue is the 6 letter word TALKER
I've seen this crossword clue in The Daily Telegraph
T
A
L
K
E
R
More clues leading to the result TALKER
Buddy explains!

The straight part
We know that "speaker" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case speaker = talker.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 TALKER mean?
TALKER noun- A person who talks, especially one who gives a speech, or is loquacious or garrulous.
- Any creature or machine that talks.
- A talk show
- A talk-show host.
- An all-talk radio station.
- A popular topic of conversation.
- A talking point.
- A stripped-down version of a MUD which is designed for talking, predating instant messengers; a kind of early chat room.
- Mouth.