Celebrate birthday partly around family (5)
I believe the answer is:
tribe
'family' is the definition.
(I've seen this in other clues)
'celebrate birthday partly around' is the wordplay.
'partly' indicates the answer is hidden within the clue (part of the clue is used).
'around' says the letters should be written in reverse.
'ebirt' is hidden in the letters of 'celebrate birthday'.
'ebirt' back-to-front is 'TRIBE'.
(Other definitions for tribe that I've seen before include "A set or class of people, may be primitive" , "Race" , "Ethnic grouping" , "Division of, eg, North American natives" , "Group of people with a common culture" .)