I zip pack, containing fractions? (6)
I believe the answer is:
ratios
'fractions?' is the definition.
(I've seen this in another clue)
'i zip pack containing' is the wordplay.
'zip' becomes 'o' (zip can mean zero).
'pack' becomes 'rats' (I can't explain this - if you can you should believe this answer much more).
'containing' is an insertion indicator.
'i'+'o'='io'
'io' inserted within 'rats' is 'RATIOS'.
Can you help me to learn more?
(Other definitions for ratios that I've seen before include "Relative magnitudes of quantities" , "Proportional relations" , "Relationships between two amounts" .)