Register point over US earthquake, not very impressive (5)
I believe the answer is:
enter
'register' is the definition.
(entering is a kind of registering)
'point over us earthquake not very impressive' is the wordplay.
'point over us earthquake' becomes 'epicenter' (US spelling of epicentre).
'not' suggests deleting specific letters.
'very impressive' becomes 'epic' (I've seen this before).
'epicenter' with 'epic' taken away is 'ENTER'.
(Other definitions for enter that I've seen before include "Make a record of" , "Break in" , "Treen (anag.)" , "Fruit drink" , "Take part in a contest" .)