hamstring (v.) Look up hamstring at Dictionary.com
1640s, "to disable, render useless," a figurative verbal extension from the noun hamstring "tendon at the back of the knee" (1560s), from ham "bend of the knee" (see ham (n.1)) + string. Cutting this would render a person or animal lame. Related: Hamstrung.
[I]n hamstring, -string is not the verb string; we do not string the ham, but do something to the tendon called the hamstring; the verb, that is, is made not from the two words ham & string, but from the noun hamstring. It must therefore make hamstringed. [Fowler]