A tiny covering so minute it's amazing (7)
I believe the answer is:
awesome
'amazing' is the definition.
('awesome' can be a synonym of 'amazing')
'a tiny covering so minute' is the wordplay.
'tiny' becomes 'wee' (I've seen this before).
'covering' means one lot of letters goes inside another.
'minute' becomes 'm' (abbreviation).
'so'+'m'='som'
'wee' going around 'som' is 'wesome'.
'a'+'wesome'='AWESOME'
'it's' acts as a link.
(Other definitions for awesome that I've seen before include "Hugely impressive, creating fear and wonder" , "Frightening but impressive" , "Portentous" , "staggering" , "Inspiring reverential fear" .)