Avoid mysterious abyss skirting beginning of prairie (6)
I believe the answer is:
bypass
'avoid' is the definition.
(bypassing is a kind of avoiding)
'mysterious abyss skirting beginning of prairie' is the wordplay.
'mysterious' indicates an anagram.
'skirting' means one lot of letters goes inside another.
'beginning of' indicates taking the first letters.
The first letter of 'prairie' is 'p'.
'abyss' is an anagram of 'byass'.
'byass' enclosing 'p' is 'BYPASS'.
(Other definitions for bypass that I've seen before include "Go around" , "What avoids Newbury" , "detour" , "Circuitous route (for traffic, fluids etc)" , "operation to improve circulation" .)