Function on back street expected award for successful party (5)
I believe the answer is:
costs
'expected award for successful party' is the definition.
I can't tell whether this definition defines the answer.
'function on back street' is the wordplay.
'function' becomes 'cos' (mathematical function).
'on' means one lot of letters go next to another (in a down clue, letters appear on others).
'back' says the letters should be written backwards.
'street' becomes 'st' (abbreviation).
'st' reversed gives 'ts'.
'cos'+'ts'='COSTS'
Can you help me to learn more?
(Other definitions for costs that I've seen before include "Is priced at" , "Fees" , "Expenditures, outlays" , "is expensive" , "Overheads" .)