It's useful for refreshment and relaxation during a race (3,3)
I believe the answer is:
tea set
'it's useful for refreshment' is the definition.
I can't tell whether this definition defines the answer.
'relaxation during a race' is the wordplay.
'relaxation' becomes 'ease' (synonyms).
'during' means one lot of letters goes inside another.
'a race' becomes 'tt'.
'ease' put into 'tt' is 'TEA-SET'.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for tea set that I've seen before include "Matching plates, cups, etc" , "hot drink service" , "Set of crockery for serving light meal" , "China for small meal" , "Collections of cups, saucers etc for serving light meal" .)