Rhea, for example, bird on a headland (8)
I believe the answer is:
titaness
'rhea for example' is the definition.
(rhea is a kind of Titaness)
'bird on a headland' is the wordplay.
'bird' becomes 'tit' (tit is a kind of bird**).
'on' means one lot of letters go next to another.
'headland' becomes 'ness' (I've seen this before).
'tit'+'a'+'ness'='TITANESS'
(Other definitions for titaness that I've seen before include "Giant goddess" , "Phoebe, say" , "big girl" , "A huge woman" , "Giant woman" .)