Way Republican president once is for industrial action (6)
I believe the answer is:
strike
'is for industrial action' is the definition.
(workers going on strike)
'way republican president' is the wordplay.
'way' becomes 'st' (abbreviation for street).
'republican' becomes 'R' (abbreviation in US politics).
'president' becomes 'ike' (nickname of Dwight Eisenhower).
'st'+'r'+'ike'='STRIKE'
'once' is the link.
(Other definitions for strike that I've seen before include "Walk out" , "Song of regret" , "Hit - down tools" , "Hit the labour withdrawal" , "Hit sharply" .)