Credit us with a fast finish, though it’s hard (5)
I believe the answer is:
crust
'it's hard' is the definition.
I can't judge whether this defines the answer.
'credit us with a fast finish' is the wordplay.
'credit' becomes 'cr'.
'with' means one lot of letters go next to another.
'finish' says to take the final letters.
The last letter of 'fast' is 't'.
'cr'+'us'+'t'='CRUST'
'though' is the link.
Can you help me to learn more?
(Other definitions for crust that I've seen before include "Pie topping" , "Bit of toast, perhaps" , "Tough part of twenty two down" , "Hardened layer; pie top" , "Hard knowledge" .)