'Dandy' encompassing the Spanish for 'fool' (6)
I believe the answer is:
delude
'fool' is the definition.
(thesaurus)
'dandy encompassing the spanish' is the wordplay.
'dandy' becomes 'dude' ('dude' can be a synonym of 'dandy').
'encompassing' means one lot of letters goes inside another.
'the spanish' becomes 'el'.
'dude' going around 'el' is 'DELUDE'.
'for' acts as a link.
(Other definitions for delude that I've seen before include "Eluded so as to deceive" , "Mislead; deceive" , "Mislead or fool" , "Cause to believe a lie" , "Kid" .)