Earth goddess's odd features of gravitas (4)
I believe the answer is:
gaia
'earth goddess's' is the definition.
(I've seen this in another clue)
'odd features of gravitas' is the wordplay.
'odd features of' indicates alternate letters (letters in odd-numbered positions).
The alternating letters of 'gravitas' are 'GAIA'.
(Other definitions for gaia that I've seen before include "The earth viewed as a large organism (Lovelock)" , "Greek goddess of the Earth" , "Earth personified" .)