More nasty fellows surrounding a queen (6)
I believe the answer is:
meaner
'more nasty' is the definition.
('mean' can be similar in meaning to 'nasty')
'fellows surrounding a queen' is the wordplay.
'fellows' becomes 'men' (I've seen this before).
'surrounding' is an insertion indicator.
'queen' becomes 'er' (abbreviation for Elizabeth Regina).
'men' placed around 'a' is 'mean'.
'mean'+'er'='MEANER'
(Other definitions for meaner that I've seen before include "Rename (anag.)" , "More stingy or parsimonious" , "Less generous" , "More miserly" , "Rename as being stingier" .)