Could be grave in a manner of speaking (6)
I believe the answer is:
accent
I believe this is a triple definition!
'could be grave' is the first definition.
(I've seen this before)
'in' is a link.
'a manner' is the second definition.
(I have seen 'manner of speaking' mean 'accent' so perhaps 'manner' could also mean 'accent')
'of' is a link.
'speaking' is the third definition.
(thesaurus)
(Other definitions for accent that I've seen before include "Stress - regional dialect" , "Mark over a vowel, perhaps" , "Stress, emphasis" , "Speech pattern" , "Emphasis on syllable or local pronunciation" .)