Expert in middle of Surrey is no crawler (5)
I believe the answer is:
racer
'no crawler' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.
'expert in middle of surrey' is the wordplay.
'expert' becomes 'ace' (ace can informally mean very good).
'in' is an insertion indicator.
'middle of' says to take the centre.
The centre of 'surrey' is 'rr'.
'ace' put within 'rr' is 'RACER'.
'is' is the link.
Can you help me to learn more?
(Other definitions for racer that I've seen before include "Fast-moving snake" , "Speedway competitor, perhaps" , "one in a hurry" , "American snake" , "sportsman" .)