Concentration points to sound state of mind (7)
I believe the answer is:
essence
'concentration' is the definition.
(thesaurus)
'points to sound state of mind' is the wordplay.
I cannot really see how this works, but
'points' could be 'ss' and 'ss' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for essence that I've seen before include "Plant extract flavouring" , "Vital element" , "SE scene (anag.)" , "Key" , "Intrinsic nature (of something)" .)