Keen to restyle a mantle (6)
I believe the answer is:
lament
'keen' is the definition.
(keen can mean to wail with grief)
'restyle a mantle' is the wordplay.
'restyle' indicates an anagram (I've seen 'restyled' mean this).
'mantle' anagrammed gives 'LAMENT'.
'to' acts as a link.
(Other definitions for lament that I've seen before include "Wail" , "Dart-throwing line" , "Cry of sorrow" , "Expression of sorrow" , "Keen" .)