Informal, off-hand (6)
I believe the answer is:
casual
I believe this is a double definition.
'informal' is the first definition.
(similar in meaning)
'off-hand' is the second definition.
(I've seen this before)
(Other definitions for casual that I've seen before include "Informal or blase" , "Informal or happening by chance" , "Informal or temporary" , "at ease" , "Occasional worker" .)