Big Eddy, top performer, clutches large mike (9)
I believe the answer is:
maelstrom
'big eddy' is the definition.
(eddy can mean a whirlpool or maelstrom)
'top performer clutches large mike' is the wordplay.
'top performer' becomes 'maestro' (maestro can mean a distinguished musician).
'clutches' indicates putting letters inside.
'large' becomes 'L' (eg in clothes sizes).
'mike' becomes 'M' (phonetic alphabet: alpha, bravo, charlie etc.).
'maestro' enclosing 'l' is 'maelstro'.
'maelstro'+'m'='MAELSTROM'
(Other definitions for maelstrom that I've seen before include "confused state of affairs" , "Whirlpool, turmoil" , "disorder" , "extreme turbulence" , "Powerful circular current of water" .)