Figure of 'ostility, say (5)
I believe the answer is:
eight
'figure' is the definition.
(I've seen this in other clues)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for eight that I've seen before include "1,001 - 993" , "Cube of two" , "Rowing boat crew" , "One over this for drunkeness" , "Number (with pieces?)" .)