Begin to understand amount exposed (6,3)
I believe the answer is:
figure out
'begin to understand' is the definition.
'amount exposed' is the wordplay.
'amount' becomes 'figure' (figure is a kind of amount**).
'exposed' becomes 'out' (I've seen this in other clues).
'figure'+'out'='FIGURE OUT'
(Other definitions for figure out that I've seen before include "understand?" , "Calculate - fathom" , "Reckon" .)