Sly or crafty (for two).
Sharp, cunning, intelligent. (For three more)
The word cagy is a synonym for clever in the sense of being smart.
limn
Ache is a synonym for empathize.
A-one, Tops.
Work is a synonym for task.
ague
idea, heed, or view
myth
Pots, cuts, raps, rips
lies
glib
Armor is a 5-letter word starting with A that means "mail," as in chain mail armor worn by medieval knights.
F is also the first letter of the synonym "faux" (meaning false or imitation). M is the first letter of the word "mock" (same connotation as faux).