A number are inclined not to finish (3)
I believe the answer is:
ten
'a number' is the definition.
(ten is a number)
'are inclined not to finish' is the wordplay.
'are inclined' becomes 'tend' (I've seen this in another clue).
'not to finish' means to remove the last letter.
'tend' with its final letter taken off is 'TEN'.
(Other definitions for ten that I've seen before include "Dudley Moore/Bo Derek film" , "How many" , "No of sides of a decagon" , "X-WORD" , "Half a score" .)