Mendelssohn's turbulent life and times? (5)
I believe the answer is:
felix
'mendelssohn's' is the definition.
(composer Felix Mendelssohn)
'turbulent life and times?' is the wordplay.
'turbulent' indicates anagramming the letters.
'and' is a charade indicator (letters next to each other).
'times?' becomes 'x' (2 times 4 is 2 x 4).
'life' is an anagram of 'feli'.
'feli'+'x'='FELIX'
(Other definitions for felix that I've seen before include "M. name, literally happy" , "Chap" .)