Concerning muscle contractions, getting treated is costly (8)
I believe the answer is:
systolic
'concerning muscle contractions getting' is the definition.
I can't judge whether this defines the answer.
'treated is costly' is the wordplay.
'treated' is an anagram indicator.
'is'+'costly'='iscostly'
'iscostly' anagrammed gives 'SYSTOLIC'.
Can you help me to learn more?
(Other definitions for systolic that I've seen before include "Relating to the heart's contracting phase" , "on the beat" , "Blood pressure when the heart is contracting" , "To do with rhythmic contraction of heart chambers" .)