Queen barred from engaging, mostly, with bit of effervescence in bowel (9)
I believe the answer is:
intestine
'bowel' is the definition.
(synonyms)
'queen barred from engaging mostly with bit of effervescence in' is the wordplay.
I cannot really understand how this works, but
'from' could be 'in' (I've seen this in other clues) and 'in' is present in the answer.
'in' is within the answer.
The remaining letters 'teste' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
(Other definitions for intestine that I've seen before include "Being gutted, one loses it" , "Some guts" , "Part of the alimentary canal" , "canal section" .)