More nasty fellows surrounding a queen (6)
I believe the answer is:
Here is my best explanation:
'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'.
(Other definitions for meaner that I've seen before include "More stingy or parsimonious", "Rename as being stingier", "Rename (anag.)", "Less generous", "Stingier", "Rename as being more stingy" and "More miserly".)