Guy taking in the Spanish dupe (6)
I believe the answer is:
delude
'dupe' is the definition.
(I've seen this in another clue)
'guy taking in the spanish' is the wordplay.
'guy' becomes 'dude' (both can informally mean a man).
'taking in' indicates putting letters inside.
'the spanish' becomes 'el' ('the' in Spanish).
'dude' placed around 'el' is 'DELUDE'.
(Other definitions for delude that I've seen before include "Lead into false belief" , "Mislead or fool" , "Deceive, lead on" , "swindle" , "Cause to believe a lie" .)