Political group crossing line? Not entirely (6)
I believe the answer is:
partly
'entirely' is the definition.
Both the answer and definition are adverbs. Perhaps you can see a link between them that I can't see?
'political group crossing line?' is the wordplay.
'political group' becomes 'party' (a political party).
'crossing' means one lot of letters goes inside another (to cross can mean to go over or around).
'line?' becomes 'l' (used when specifying particular lines from a poem).
'party' enclosing 'l' is 'PARTLY'.
'not' acts as a link.
Can you help me to learn more?
(Other definitions for partly that I've seen before include "Moderately" , "Somewhat" , "Not quite" , "'In some degree, not wholly (6)'" , "To some extent, not wholly" .)