God! That’s not half thorough (4)
I believe the answer is:
thor
'god' is the definition.
(Thor is an example)
'not half thorough' is the wordplay.
'not half' indicates taking half.
'thorough' cut in half is 'THOR'.
'that's' acts as a link.
(Other definitions for thor that I've seen before include "Scandinavian god of thunder and the weather" , "Germanic deity" , "The Thunderer" , "Comic superhero" , "Norse hammer-wielding god" .)