Sweet father the difference between US and UK labour: 'It's a boy!' (5,5)
I believe the answer is:
fruit salad
'sweet father the difference between us' is the definition.
I can't tell whether this defines the answer.
'uk labour it's a boy' is the wordplay.
'uk labour' becomes 'fruits' (I can't justify this - if you can you should believe this answer much more).
'boy' becomes 'lad' (informal term for boy).
'fruits'+'a'+'lad'='FRUIT SALAD'
'and' is the link.
Can you help me to learn more?
(Other definitions for fruit salad that I've seen before include "Dessert served in syrup or juice" , "Oranges and Lemons etc" , "Possibly healthy dessert" .)