Dogs I have not seen as separate characters? (7)
I believe the answer is:
cursive
'not seen as separate characters?' is the definition.
(cursive writing joins up letters or characters)
'dogs i have' is the wordplay.
'dogs' becomes 'curs' (cur can mean a violent dog).
'i have' becomes 'I've' (contraction of 'I have').
'curs'+'ive'='CURSIVE'
(Other definitions for cursive that I've seen before include "Joined-up (writing)" , "script" .)