An attic is obviously quite high (5)
I believe the answer is:
aloft
'obviously quite high' is the definition.
'aloft' can be an answer for 'high' (I've seen this in another clue). I am not certain of the 'obviously quite' bit.
'an attic' is the wordplay.
'an' becomes 'a'.
'attic' becomes 'loft' (synonyms).
'a'+'loft'='ALOFT'
'is' is the link.
Can you help me to learn more?
(Other definitions for aloft that I've seen before include "Heading for heaven" , "Up in the sky" , "At a considerable height" , "Up in the air, high above" , "Float (anag.)" .)