Bowler say in with Atherton (3)
I believe the answer is:
hat
'bowler' is the definition.
(I've seen this in other clues)
'in with atherton' is the wordplay.
'in' says the answer is hidden in the clue.
'HAT' can be found hidden inside 'with atherton'.
'say' acts as a link.
(Other definitions for hat that I've seen before include "Bowler maybe" , "opera?" , "Headwear" , "Eg, derby" , "Cloche or fez?" .)