Approach in hybridising the quince? (9)
I believe the answer is:
technique
'approach' is the definition.
(thesaurus)
'hybridising the quince?' is the wordplay.
'hybridising' indicates an anagram (letters hybridised or mixed up).
'the'+'quince'='thequince'
'thequince' with letters rearranged gives 'TECHNIQUE'.
'in' acts as a link.
(Other definitions for technique that I've seen before include "Practical procedure" , "Way of carrying our a task" , "Skilled procedure or method" , "way of proceeding" , "Way of doing something" .)