Turtle starting to poke through land (8)
I believe the answer is:
terrapin
'turtle' is the definition.
(terrapin is a kind of turtle)
'starting to poke through land' is the wordplay.
'starting to' says to take the initial letters.
'through' means one lot of letters goes inside another (I've seen this in other clues).
'land' becomes 'terrain' (I've seen this before).
The initial letter of 'poke' is 'p'.
'p' inserted within 'terrain' is 'TERRAPIN'.
(Other definitions for terrapin that I've seen before include "Small species of turtle" , "Chelonian reptile" , "Hardback" , "A reptile; a printer (anag.)" , "Web-footed turtle" .)