Claimant legally keeping sleeveless cloak (6)
I believe the answer is:
mantle
'sleeveless cloak' is the definition.
(I've seen this in another clue)
'claimant legally keeping' is the wordplay.
'keeping' says the answer is hidden in the clue.
'MANTLE' can be found hidden inside 'claimant legally'.
(Other definitions for mantle that I've seen before include "Loose cloak, shawl" , "Gas lamp part; cloak" , "Cloak and shelf over the fireplace" , "Layer below earth's crust" , "Goes over light" .)