Celebration outside Leatherhead? Not entirely (6)
I believe the answer is:
partly
'not entirely' is the definition.
Both the definition and answer are adverbs.
Perhaps there's an association between them I don't understand?
'celebration outside leatherhead?' is the wordplay.
'celebration' becomes 'party' (I've seen this before).
'outside' indicates putting letters inside (some letters go outside others).
'leatherhead?' becomes 'l' (head letter of 'leather').
'party' going around 'l' is 'PARTLY'.
Can you help me to learn more?
(Other definitions for partly that I've seen before include "To some extent, not wholly" , "'In some degree, not wholly (6)'" , "to a certain degree" , "Moderately" , "Somewhat" .)