High attic required by youth leader (5)
I believe the answer is:
lofty
'high' is the definition.
(similar in meaning)
'attic required by youth leader' is the wordplay.
'attic' becomes 'loft' (synonyms).
'required by' is a charade indicator (letters next to each other).
'leader' says to take the initial letters.
The first letter of 'youth' is 'y'.
'loft'+'y'='LOFTY'
(Other definitions for lofty that I've seen before include "Soaring" , "Of majestic height" , "Exalted" , "Eminent" , "Noble, elevated" .)