Badly wanted to pursue prince (was a tosser) (7)
I believe the answer is:
pitched
'was a tosser' is the definition.
(pitch can mean to toss something)
'badly wanted to pursue prince' is the wordplay.
'badly wanted' becomes 'itched' (to itch for something is to want it really badly).
'to pursue' says to put letters next to each other.
'prince' becomes 'p' (abbreviation).
'itched' after 'p' is 'PITCHED'.
(Other definitions for pitched that I've seen before include "Threw" , "cast" , "Set on a particular musical note" .)