Instrument from band grabbed by excited chairman (9)
I believe the answer is:
harmonica
'instrument' is the definition.
(harmonica is a kind of instrument)
'band grabbed by excited chairman' is the wordplay.
'band' becomes 'o' (I've seen this in other clues).
'grabbed by' means one lot of letters goes inside another.
'excited' indicates an anagram.
'chairman' with letters rearranged gives 'harmnica'.
'o' going into 'harmnica' is 'HARMONICA'.
'from' acts as a link.
(Other definitions for harmonica that I've seen before include "glasses of water" , "Larry Adler's instrument" , "Harp" , "Blow me!" , "musical instrument" .)