Ancestral line of woman in exercise class, mostly inexperienced (8)
I believe the answer is:
pedigree
'ancestral line' is the definition.
(I've seen this in another clue)
'of woman in exercise class mostly inexperienced' is the wordplay.
'of woman' becomes 'di' (I can't explain this - if you can you should believe this answer much more).
'in' is an insertion indicator.
'exercise class' becomes 'pe' (physical education).
'mostly' means to remove the last letter (most but not all of the word).
'inexperienced' becomes 'green' (similar in meaning).
'green' with its final letter removed is 'gree'.
'pe'+'gree'='pegree'
'di' put within 'pegree' is 'PEDIGREE'.
Can you help me to learn more?
(Other definitions for pedigree that I've seen before include "bloodline" , "High-class" , "Line of descent, family tree" , "Line of decent or ancestry" , "Line of ancestry, particularly a distinguished one" .)