Party time for Dorothy (3)
I believe the answer is:
dot
'dorothy' is the definition.
(nickname for someone called Dorothy)
'party time' is the wordplay.
'party' becomes 'do' (do is a kind of party).
'time' becomes 't' (abbreviation).
'do'+'t'='DOT'
'for' is the link.
(Other definitions for dot that I've seen before include "Morse symbol; spot" , "Speck; dowry" , "Small round spot" , "One signal used in Morse code" , "Shorter of the two signals used in Morse code" .)