Current queen is not commonly brief (8)
I believe the answer is:
acquaint
'commonly brief' is the definition.
'acquaint' can be an answer for 'brief' (thesaurus). I am unsure of the 'commonly' bit.
'current queen is not' is the wordplay.
'current' becomes 'ac' (alternating current).
'queen' becomes 'qu'.
'is not' becomes 'aint' (I've seen this before).
'ac'+'qu'+'aint'='ACQUAINT'
Can you help me to learn more?
(Other definitions for acquaint that I've seen before include "Make aware or familiar with, say the facts" , "get up to date" , "American to introduce" , "Get familiar" , "Inform" .)