Each year family business ultimately is worth doing (4)
I believe the answer is:
pays
'is worth doing' is the definition.
(I've seen this in another clue)
'each year family business ultimately' is the wordplay.
'each year' becomes 'PA' (abbreviation for per annum).
'ultimately' says to take the final letters.
The last letters of 'family business' are 'ys'.
'pa'+'ys'='PAYS'
(Other definitions for pays that I've seen before include "Is profitable, country (Fr.)" , "Imburses" , "Benefits" , "stumps up" , "(13) [FRENCH] Country" .)