Do some before the end of May (5)
I believe the answer is:
party
'do' is the definition.
(thesaurus)
'some before the end of may' is the wordplay.
'some' becomes 'part'.
'before' means one lot of letters go next to another.
'the end of' says to take the final letters.
The final letter of 'may' is 'y'.
'part'+'y'='PARTY'
(Other definitions for party that I've seen before include "Crew" , "push the boat out" , "Social function" , "Festivity" , "Social occasion - political group" .)