  We evaluate perturbative next-to-leading order corrections to the hard
exclusive leptoproduction of pi+ mesons on a transversely polarized proton
target. A model dependent study shows that these corrections can be large. We
analyze the scale dependence and explore the Brodsky-Lepage-Mackenzie scale
setting procedure. Although the predictions for the cross section suffer from
theoretical uncertainties, the transverse nucleon single spin asymmetry turns
out to be a rather stable observable since higher order effects approximately
cancel there.
