The other side of a circle shown by black lines (7)
I believe the answer is:
obverse
'the other side' is the definition.
(thesaurus)
'a circle shown by black lines' is the wordplay.
'a circle' becomes 'O' (O is a circle).
'shown by' is a charade indicator (letters next to each other).
'black' becomes 'b' (as in pencil classifications).
'lines' becomes 'verse' (lines of poetry).
'o'+'b'+'verse'='OBVERSE'
'of' acts as a link.
(Other definitions for obverse that I've seen before include "Serving as a counter-part" , "Penny may present such a face" , "Logical proposition" , "Coin's head side" , "Opposite - side of coin" .)