It measures resistance only initially encountered between queens (8)
I believe the answer is:
ohmmeter
'it measures resistance' is the definition.
(device for measuring electrical resistance)
'only initially encountered between queens' is the wordplay.
I cannot really understand how this works, but
'encountered' could be 'met' ('meet' can be a synonym of 'encounter') and 'met' is present in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for ohmmeter that I've seen before include "Meter for measuring electrical resistance" , "Instrument to measure electrical resistance" , "What'll show resistance" , "Instrument measuring electrical resistance" , "Measurer of electrical resistance" .)