Making new version of Annie's hard, even a one-off musical (4)
'musical' is the definition.
'making new version of annie's hard even a one-off' is the wordplay.
'making new version of' indicates an anagram.
'one' becomes 'i' (Roman numeral).
'off' indicates named letters should be taken away.
'annies'+'hard'+'even'+'a'='annieshardevena'
'annieshardevena' with 'i' removed is 'anneshardevena'.
'anneshardevena' anagrammed gives 'DEAR EVAN HANSEN'.
'musical' is the definition.
Both the definition and answer are adjectives. Maybe they are linked in a way I don't understand?
I can't explain the remainder of the clue.
(Other definitions for dear that I've seen before include "address for partner" , "Expensive -- honey" , "It's not cheap" , "Beloved - expensive" , "Needing plenty of bread" .)