Hit (verb): affect badly
Key (adjective): essential, vital
Link: connection
Move: step towards a desired end
Ordeal (noun): painful experience
Oust (verb): push out/ remove
Plea (noun): request
Pledge: promise
Ploy (noun): clever activity
Poll: erection, public opinion survey
Probe: investigation
Quit (verb): leave, resign
Riddle (noun): mystery
Strife (noun): conflict
Talks (noun): discussions
Threat: danger
Vow: promise
Wed (verb): marry

(Source: English Vocabulary in Use, Cambridge Press)