Spots the Queen's bit of bacon (6)
I believe the answer is:
rasher
'bit of bacon' is the definition.
(I've seen this before)
'spots the queen's' is the wordplay.
'spots' becomes 'rash' (as in skin irritation).
'the queen' becomes 'ER' (abbreviation for Elizabeth Regina).
'rash'+'er'='RASHER'
(Other definitions for rasher that I've seen before include "more headstrong" , "breakfast selection?" , "American fish" , "eat this?" , "More impetuous - slice of meat" .)