hasten

hasten /ˈheɪsn̩/ verb
hastens; hastened; hastening
hasten
/ˈheɪsn̩/
verb
hastens; hastened; hastening
Britannica Dictionary definition of HASTEN
1 
[+ object] : to cause (something) to happen more quickly
2 
[no object] old-fashioned : to move or act quickly

hasten to add/say/explain (etc.)

: to immediately say something in order to prevent confusion or misunderstanding