Pretty self-contained initially, and somehow nice (6)
I believe the answer is:
scenic
'pretty' is the definition.
(thesaurus)
'self-contained initially and somehow nice' is the wordplay.
'initially' says to take the initial letters.
'and' is a charade indicator (letters next to each other).
'somehow' indicates anagramming the letters.
The initial letters of 'self contained' is 'sc'.
'nice' with letters rearranged gives 'enic'.
'sc'+'enic'='SCENIC'
(Other definitions for scenic that I've seen before include "Such a railway" , "having a striking view" , "Having nice views along the route" , "Picturesque, beautiful" , "This route has picturesque views" .)