Dead right, perhaps, but not yet (5)
I believe the answer is:
later
'not yet' is the definition.
(I've seen this in another clue)
'dead right perhaps' is the wordplay.
'dead' becomes 'late' (similar in meaning).
'right perhaps' becomes 'r' (common abbreviation. I am not sure about the 'perhaps' bit.).
'late'+'r'='LATER'
'but' acts as a link.
Can you help me to learn more?
(Other definitions for later that I've seen before include "Not just yet" , "Alter (anag.)" , "After a given point in time" , "succeeding" , "Alert (anag.)" .)