150 and on strike, demonstrating power (5)
I believe the answer is:
clout
'power' is the definition.
(I've seen this before)
'150 and on strike' is the wordplay.
'150' becomes 'CL' (Roman numerals).
'and' means one lot of letters go next to another.
'on strike' becomes 'out' (I've seen this before).
'cl'+'out'='CLOUT'
'demonstrating' acts as a link.
(Other definitions for clout that I've seen before include "Box" , "Hit - influence" , "Punch; influence" , "piece of clothing" , "weight" .)