The Collaborative International Dictionary of English v.0.48:

Dandify \Dan"di*fy\, v. t. [imp. & p. p. Dandified; p. pr. &
   vb. n. Dandifying.] [Dandy + -fy.]
   To cause to resemble a dandy; to make dandyish.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dandify
    v 1: dress like a dandy