Sooner than finish nowhere! (3)
I believe the answer is:
ere
'sooner' is the definition.
Both the definition and answer are adverbs. Perhaps you can see an association between them that I can't see?
'than finish nowhere' is the wordplay.
'than' becomes 'er' (I can't justify this - if you can you should believe this answer much more).
'finish' suggests the final letters.
The final letter of 'nowhere' is 'e'.
'er'+'e'='ERE'
Can you help me to learn more?
(Other definitions for ere that I've seen before include "Before (in poetry)" , "Before (lit.)" , "Before (in time)" , "Before (poetic)" , "Old word for before" .)