Clear answers billions initially work out (7)
I believe the answer is:
Here is my best explanation:
'clear' is the definition.
'answers billions initially work out' is the subsidiary indication.
'initially' says to take the initial letters.
'work out' becomes 'solve' (I've seen this before).
The first letters of 'answers billions' is 'ab'.
(Other definitions for absolve that I've seen before include "Lob vase (anag.)", "Grant remission of sins", "Declare to be free from blame", "Declare (someone) guilt-free", "Exonerate", "Declare (someone) blameless", "Clear of blame or quilt", "Pardon", "Fully pardon" and "Grant pardon for".)