Topless characters felt line should be banter (8)
I believe the answer is:
raillery
'banter' is the definition.
('raillery' can be a synonym of 'banter')
'topless characters felt line' is the wordplay.
'topless' means to remove the first letter.
'characters felt' becomes 'braille' (characters felt by touch).
'line' becomes 'ry' (abbreviation for railway).
'braille' with its first letter taken off is 'raille'.
'raille'+'ry'='RAILLERY'
'should be' is the link.
(Other definitions for raillery that I've seen before include "Badinage" , "Playful satire" , "(Example of) banter" , "Light teasing repartee" , "Banter, back-chat" .)