Sensitive — difficult (6)
I believe the answer is:
tricky
This clue is a double definition.
'sensitive' is the first definition.
(thesaurus)
'difficult' is the second definition.
(similar in meaning)
(Other definitions for tricky that I've seen before include "Awkwardly difficult" , "Difficult; sly" , "Crafty; needing skill" , "Problematic - deceitful" , "Crafty, cunning" .)