Essentially crass female’s a bit of a pig (6)
I believe the answer is:
rasher
'a bit of a pig' is the definition.
(I've seen this before)
'essentially crass female's' is the wordplay.
'essentially' says to take the centre.
'female' becomes 'her' (I've seen this before).
The middle letters of 'crass' are 'ras'.
'ras'+'her'='RASHER'
(Other definitions for rasher that I've seen before include "More foolhardy than a slice of bacon" , "more headstrong" , "Less-considered" , "American fish" , "item at breakfast" .)