Labour leader got wise (7)
I believe the answer is:
learned
'wise' is the definition.
(I've seen this before)
'labour leader got' is the wordplay.
'leader' says to take the initial letters.
'got' becomes 'earned' (earning is a kind of getting**).
The first letter of 'labour' is 'l'.
'l'+'earned'='LEARNED'
(Other definitions for learned that I've seen before include "Gained understanding" , "Well-educated" , "Was taught" , "Knowledgeable - scholarly" , "Gained knowledge" .)