WordNet sense 1 (keep in a certain state, position, or activity; e.g.):

hold, keep

WordNet sense 2 (keep in safety and protect from harm, decay, loss, or destruction):

conserve, preserve, conserve, keep up

WordNet sense 3 (have and exercise):

exert, wield

WordNet sense 4 (supply with necessities and support):

sustain

WordNet sense 5 (state or assert):

defend

WordNet sense 6 (state categorically):

assert, asseverate

WordNet sense 7 (support against an opponent):

uphold

WordNet sense 8 (observe correctly or closely):

observe