Old English queen full of fever? Not so certain (6)
I believe the answer is:
vaguer
'not so certain' is the definition.
I can't judge whether this defines the answer.
'old english queen full of fever?' is the wordplay.
'old english queen' becomes 'vr' (I can't justify this - if you can you should believe this answer much more).
'full of' is an insertion indicator.
'fever?' becomes 'ague' (illness causing fever).
'vr' placed around 'ague' is 'VAGUER'.
Can you help me to learn more?
(Other definitions for vaguer that I've seen before include "increasingly rough" , "Less well defined" .)