The Collaborative International Dictionary of English v.0.48:
Prest \Prest\, a. [OF. prest, F. pr[^e]t, fr. L. praestus ready.
1. Ready; prompt; prepared. [Obs.]
All prest to such battle he was. --R. of
2. Neat; tidy; proper. [Obs.] --Tusser.
Prest money, money formerly paid to men when they enlisted
into the British service; -- so called because it bound
those that received it to be ready for service when called