A queen forbidding great passion (6)
I believe the answer is:
ardour
'great passion' is the definition.
(I've seen this before)
'a queen forbidding' is the wordplay.
'queen' becomes 'r' (abbreviation for regina, e.g. in ER ).
'forbidding' becomes 'dour' (I've seen this in another clue).
'a'+'r'+'dour'='ARDOUR'
(Other definitions for ardour that I've seen before include "Fervency" , "Enthusiasm or warmth of passion" , "Intense eagerness" , "Passionate warmth" , "Fervour, zeal" .)