Supports whip showing character (9)
I believe the answer is:
backslash
'character' is the definition.
(type of symbol)
'supports whip' is the wordplay.
'supports' becomes 'backs' ('back' can be a synonym of 'support').
'whip' becomes 'lash' (synonyms).
'backs'+'lash'='BACKSLASH'
'showing' is the link.
(Other definitions for backslash that I've seen before include "character" , "//www.crosswordgiant.com/crossword-clue/1252911/" , "line on computer screen" , "Mark" , "One leaning to the left" .)