Stigma involving Queen creates tense situation (6)
I believe the answer is:
strain
'tense situation' is the definition.
'strain' can be an answer for 'tense' ('strain' can be a synonym of 'tense'). I am not sure about the 'situation' bit.
'stigma involving queen' is the wordplay.
'stigma' becomes 'stain' ('stain' can be a synonym of 'stigma').
'involving' means one lot of letters goes inside another.
'queen' becomes 'r' (r is abbreviation regina. e.g. in ER ).
'stain' going around 'r' is 'STRAIN'.
'creates' acts as a link.
Can you help me to learn more?
(Other definitions for strain that I've seen before include "Mental tension, stress" , "Pressure - filter" , "Muscle injury, put liquid through sieve" , "Sift" , "Muscle injury - tension" .)