Laments of the French in unruly siege (7)
I believe the answer is:
elegies
'laments' is the definition.
('elegy' can be a synonym of 'lament')
'the french in unruly siege' is the wordplay.
'the french' becomes 'le' ('the' in French).
'in' indicates putting letters inside.
'unruly' is an anagram indicator.
'siege' is an anagram of 'egies'.
'le' placed into 'egies' is 'ELEGIES'.
'of' is the link.
(Other definitions for elegies that I've seen before include "Laments for the dead" , "Poems of mourning" , "Lamenting poems" , "Mourning songs" .)