Sheer excess brings a bit of pleasure to a girl (8)
I believe the answer is:
plethora
'sheer excess' is the definition.
'plethora' can be an answer for 'excess' (I've seen this before). I'm not sure about the 'sheer' bit.
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for plethora that I've seen before include "Over-fullness, excess" , "flood" , "Glut, over-abundance" , "opposite of scarcity" , "Superabundance" .)