Green’s Dictionary of Slang

up front adj.

also in front, out front, upfront

1. (orig. US) open, honest.

[US](con. 1958) R. Farina Been Down So Long (1972) 98: It’s all in front, man, they have a heart thing going for them.
[US]T. Wolfe Electric Kool-Aid Acid Test (1969) 53: A community of intelligent, very open, out-front people — out front was a term everybody was using — out-front people who cared deeply for one another.
[US]E. Tidyman Shaft 126: Up front, baby. I’m up front with you.
[US]Current Sl. VI 8: Out front, adj. Sincere; honest.
[UK]T. Blacker Fixx 306: Our friend [...] being in fact a bit of a wimpo when it comes to an up-front confrontation.
[UK]K. Sampson Powder 112: Both Tom and Malky had been very upfront, but they weren’t prepared to take less than their rate now.
[UK]J.J. Connolly Layer Cake 110: Scousers are very similar to true Londoners, flash, up-front and knowing.
[US]R. Price Lush Life 169: Could we have been any more up-front about how it went down?

2. in the foreground; foremost.

[US]Newsweek 19 Feb. 33: The up-front concern now is to improve economic and social conditions for blacks in the urban ghettos.