Round Table occasionally upset over attack (4,3)
I believe the answer is:
lash out
'attack' is the definition.
(I've seen this before)
'round table occasionally upset over' is the wordplay.
'round' becomes 'shout' (shout can mean a round of drinks in a pub).
'occasionally' indicates alternate letters (letters taken at regular intervals or occasions).
'upset' is a reversal indicator.
'over' is a charade indicator (letters next to each other) (in a down clue, some letters go over others).
The alternating letters of 'table' are 'al'.
'al' backwards is 'la'.
'shout' after 'la' is 'LASH OUT'.
(Other definitions for lash out that I've seen before include "Spend lots" , "spend a fortune" , "Recklessly spend" , "Vigorously attack" , "React violently" .)