100 scream over rock tune (7)
I believe the answer is:
century
'100' is the definition.
(synonyms)
'scream over rock tune' is the wordplay.
'scream' becomes 'cry' (synonyms).
'over' means one lot of letters goes inside another.
'rock' indicates anagramming the letters (the solver must 'rock' the letters around).
'tune' anagrammed gives 'entu'.
'cry' placed around 'entu' is 'CENTURY'.
(Other definitions for century that I've seen before include "One hundred years" , "lot of time" , "Period of time" , "Group of a hundred" , "100 years" .)