Deceived duke trapped in Spanish province (3,2)
I believe the answer is:
led on
'deceived' is the definition.
('lead on' can be a synonym of 'deceive')
'duke trapped in spanish province' is the wordplay.
'duke' becomes 'd' (abbreviation).
'trapped in' indicates putting letters inside.
'spanish province' becomes 'Leon' (province of Spain).
'd' inserted within 'leon' is 'LED ON'.
(Other definitions for led on that I've seen before include "Took for a ride" , "Persuaded - tricked" , "Unwisely enticed" , "deceived" , "was encouraging" .)