A psalm is about something in our blood (6)
I believe the answer is:
plasma
'blood' is the definition.
(thesaurus)
'a psalm is about' is the wordplay.
'is about' is an anagram indicator.
'a'+'psalm'='apsalm'
'apsalm' anagrammed gives 'PLASMA'.
'something in our' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for plasma that I've seen before include "Star material" , "Component of TV screen" , "Hot ionised gas" , "Clear fluid portion of blood" , "Screens of some TVs" .)