Percussionist Mike implicated in dreadful murder (7)
I believe the answer is:
drummer
'percussionist' is the definition.
(drummer is a kind of percussionist)
'mike implicated in dreadful murder' is the wordplay.
'mike' becomes 'M' (phonetic alphabet: alpha, bravo, charlie etc.).
'implicated in' means one lot of letters goes inside another.
'dreadful' indicates anagramming the letters.
'murder' is an anagram of 'drumer'.
'm' going inside 'drumer' is 'DRUMMER'.
(Other definitions for drummer that I've seen before include "Band member" , "Group member" , "Timpani beater" , "One using sticks" , "Rich, say" .)