I think these are correct but would appreciate help with the parsing......
27a. Steer clear of old nurse injecting drugs? Quite the opposite (5) - EVADE (Steer clear of)
2d. Venomous creature seen in box one musician keeps hidden (3,5) - Pit Viper (Venomous creature)
I get the 'musicians pit' part but not viper.
5d. Hip replacement for the queen arranged, say, finally (5) - TRENDY (Hip)
17d. One said originally to posses hard grip (8) - ADHESION (Grip)