
1) Fipple flute 2) Pipe organ component 3) Plug 4) Stopper 5) Stopple 
Found on 
https://www.crosswordclues.com/clue/fipple

 A fipple is a constricted mouthpiece common to many end-blown flutes, such as the tin whistle and the recorder. These instruments are known variously as fipple flutes, duct flutes, or tubular-ducted flutes. ==How it works== In the accompanying illustration of the head of a recorder, the wooden fipple plug (A), with a `ducted flue` windway above .....
Found on 
http://en.wikipedia.org/wiki/Fipple

plug in the mouthpiece of a wind instrument
Found on 
http://phrontistery.info/f.html

• (n.) A stopper, as in a wind instrument of music.
Found on 
http://thinkexist.com/dictionary/meaning/fipple/
 Fip'ple
Fip'ple (fẽr) 
 noun [ perh. from Latin 
 fibula a clasp, a pin; confer Prov. English 
 fible a stick used to stir pottage.] A stopper, as in a wind instrument of music. [ Obsolete] 
 Bacon. Found on 
http://www.encyclo.co.uk/webster/F/32

a word meaning the sharp edge of the lip (of a flute or recorder).
Found on 
http://www.hobgoblin-usa.com/info/glossary.htm

[
n] - a wooden plug forming a flue pipe (as the mouthpiece of a recorder)
Found on 
http://www.webdictionary.co.uk/definition.php?query=fipple
 noun
 noun a wooden plug forming a flue pipe (as the mouthpiece of a recorder)
Found on 
https://www.encyclo.co.uk/local/20974

a plug stopping the upper end of a pipe, as a recorder or a whistle, and having a narrow slit through which the player blows.
Found on 
https://www.infoplease.com/dictionary/fipple
  No exact match found.