Sign sick note for char (5)
I believe the answer is:
singe
'char' is the definition.
(thesaurus)
'sign sick note' is the wordplay.
'sick' indicates anagramming the letters.
'note' becomes 'e' (musical note).
'sign' is an anagram of 'sing'.
'sing'+'e'='SINGE'
'for' is the link.
(Other definitions for singe that I've seen before include "Result of match accident" , "Sear" , "Superficial burn" , "Result of burning" , "Lightly burn" .)