Unlikely score, 80% (4)
I believe the answer is:
tall
'unlikely' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for tall that I've seen before include "Of great stature" , "High in stature" , "Towering" , "description of a giraffe?" , "hard to believe in" .)