Servant revealed Queen essentially embarrassed by Andrew hiding evidence of sweat (6,3)
I believe the answer is:
errand boy
'servant' is the definition.
(boy employed to run errands)
'queen essentially embarrassed by andrew hiding evidence of sweat' is the wordplay.
'queen' becomes 'ER' (abbreviation for Elizabeth Regina).
'essentially embarrassed by andrew' becomes 'randy' (I am not sure about this - if you are sure you should believe this answer much more).
'hiding' is an insertion indicator.
'evidence of sweat' becomes 'BO' (body odour).
'randy' enclosing 'bo' is 'randboy'.
'er'+'randboy'='ERRAND BOY'
'revealed' acts as a link.
Can you help me to learn more?
(Other definitions for errand boy that I've seen before include "fag?" , "Delivery lad" , "Young assistant" , "One delivering shopkeeper's goods" , "One making, eg, deliveries" .)