It's a blow, being dismissed at 150! (5)
I believe the answer is:
clout
'it's a blow' is the definition.
(I've seen this in another clue)
'dismissed at 150' is the wordplay.
'dismissed' becomes 'out' (dismissed in cricket).
'at' is a charade indicator (letters next to each other) (I've seen this in other clues).
'150' becomes 'CL' (Roman numerals).
'out' after 'cl' is 'CLOUT'.
'being' acts as a link.
(Other definitions for clout that I've seen before include "Smack - influence" , "weight" , "Cuff" , "Old-fashioned garment" , "Influence; heavy blow" .)