Spanish unit houses key cultural organisation (6)
I believe the answer is:
unesco
'cultural organisation' is the definition.
(UN cultural organisation)
'spanish unit houses key' is the wordplay.
'spanish unit' becomes 'uno' (I can't explain this - if you can you should give a lot more credence to this answer).
'houses' is an insertion indicator.
'key' becomes 'esc' ('Escape' key on a computer keyboard).
'uno' going around 'esc' is 'UNESCO'.
Can you help me to learn more?
(Other definitions for unesco that I've seen before include "Body passing motions" , "United Nations agency to promote education etc" , "international group" , "World cultural and educational organisation" , "International agency -- no cues (anag)" .)