Constant European learnt in new form (7)
I believe the answer is:
eternal
'constant' is the definition.
(I've seen this in another clue)
'european learnt in new form' is the wordplay.
'european' becomes 'e' (abbreviation e.g. EU).
'in new form' indicates anagramming the letters.
'learnt' with letters rearranged gives 'ternal'.
'e'+'ternal'='ETERNAL'
(Other definitions for eternal that I've seen before include "carrying on endlessly" , "'Lasting forever, unending (7)'" , "non-stop" , "Continuing forever or indefinitely" , "with lasting benefit" .)