Understood female in diamonds (8)
I believe the answer is:
fathomed
'understood' is the definition.
(fathoming is a kind of understanding)
'female in diamonds' is the wordplay.
'female' becomes 'f' (abbreviation).
'in' becomes 'athome' ('at home' can be similar in meaning to 'in').
'diamonds' becomes 'd' (abbreviation in bridge say).
'f'+'athome'+'d'='FATHOMED'
(Other definitions for fathomed that I've seen before include "Got" , "Deeply understood" , "Sounded" .)