Melancholy way of the French footloose rich (6)
I believe the answer is:
rueful
'melancholy' is the definition.
(both can mean sorrowful)
'way of the french footloose rich' is the wordplay.
'way of the french' becomes 'rue' ('street' in French).
'footloose' means to remove the last letter (the bottom letter or 'foot' is loosened).
'rich' becomes 'full' (both can mean bountiful or abundant).
'full' with its last letter removed is 'ful'.
'rue'+'ful'='RUEFUL'
(Other definitions for rueful that I've seen before include "Regretting" , "Contrite, with regrets" , "Regretful" , "Penitent" , "Filled with regret" .)