Weep about tune played for a long time (7)
I believe the answer is:
century
'a long time' is the definition.
(thesaurus)
'weep about tune played' is the wordplay.
'weep' becomes 'cry' ('cry' can be a synonym of 'weep').
'about' indicates putting letters inside.
'played' indicates anagramming the letters.
'tune' with letters rearranged gives 'entu'.
'cry' going around 'entu' is 'CENTURY'.
'for' is the link.
(Other definitions for century that I've seen before include "Group of a hundred" , "A lot of runs!" , "100 years" , "One hundred years" , "lot of time" .)