Mothers hurry, being 16 (6)
I believe the answer is:
mashie
'16' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'mothers hurry' is the wordplay.
'mothers' becomes 'mas' (ma is a kind of mother).
'hurry' becomes 'hie' ('hie' can be a synonym of 'hurry').
'mas'+'hie'='MASHIE'
'being' is the link.
Can you help me to learn more?
(Other definitions for mashie that I've seen before include "He aims (anag) - golfer's five iron, formerly" , "Golf club for lofting" , "Old-fashioned golf club" , "One of 9 [CLUBS]" , "Old golf club" .)