Clock is etymologically related to Laugh. Laugh is related to Emotion. Emotion is related to Need. Need is the opposite of Sufficient. 
Could is related to Action. Action is related to Remain. 
Clock --EtymologicallyRelatedTo--> Laugh <--RelatedTo--> Emotion <--RelatedTo--> Need <--Antonym--> Sufficient 
Could <--RelatedTo--> Action <--RelatedTo--> Remain 