Somewhat dismal, ignominious and baleful (6)
I believe the answer is:
malign
'baleful' is the definition.
(thesaurus)
'somewhat dismal ignominious and' is the wordplay.
'somewhat' indicates a hidden word.
'MALIGN' can be found hidden inside 'dismal ignominious and'.
(Other definitions for malign that I've seen before include "Speak ill of (someone)" , "Damaging - defame" , "Speak bad of" , "Evil - slander" , "Traduce" .)