Dad's collecting new cooking equipment (4)
I believe the answer is:
pans
'cooking equipment' is the definition.
(pans are cooking vessels)
'dad's collecting new' is the wordplay.
'dad's' becomes 'pa's' (both can mean one's father).
'collecting' indicates putting letters inside.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'pas' going around 'n' is 'PANS'.
(Other definitions for pans that I've seen before include "vessels" , "kitchen equipment" , "Cooking utensils" , "roasts" , "Criticises" .)