Bristle, having drink reduced by Queen (7)
I believe the answer is:
whisker
'bristle' is the definition.
(thesaurus)
'drink reduced by queen' is the wordplay.
I cannot quite understand how this works, but
'queen' could be 'er' (abbreviation for Elizabeth Regina) and 'er' is found in the answer.
The remaining letters 'whisk' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
'having' is the link.
Can you help me to learn more?
(Other definitions for whisker that I've seen before include "Coarse hair" , "Bristle; small amount" , "Hair's breadth" , "Sensory hair of a cat" , "Hair on cat's face" .)