Queen Elizabeth Gates perhaps showing this sticker? (10)
I believe the answer is:
billposter
'elizabeth gates perhaps showing this sticker?' is the definition.
The definition suggests a singular noun which matches the answer.
'queen' is the wordplay.
I cannot really see how this works, but
'queen' could be 'er' (short for Elizabeth Regina ie Queen Elizabeth) and 'er' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for billposter that I've seen before include "One who sticks at his job" , "One pasting up advertisements" , "One who pastes up adverts on hoardings" .)