Consents but will be a long time coming round again (6)
I believe the answer is:
agrees
'consents but' is the definition.
'agrees' can be an answer for 'consents' (agreeing is a kind of consenting). I am unsure of the 'but' bit.
'a long time coming round again' is the wordplay.
'a long time' becomes 'ages' (ages can mean a very long time).
'coming round' is an insertion indicator.
'again' becomes 're' (prefix meaning 'again').
'ages' placed around 're' is 'AGREES'.
'will be' is the link.
Can you help me to learn more?
(Other definitions for agrees that I've seen before include "Accedes or concurs" , "Assents, concurs" , "Holds the same opinion" , "Grease (anag.)" , "is in accord" .)