Purchase intact or otherwise (8)
I believe the answer is:
traction
'purchase' is the definition.
(as in grip on a surface)
'intact or otherwise' is the wordplay.
'otherwise' is an anagram indicator.
'intact'+'or'='intactor'
'intactor' anagrammed gives 'TRACTION'.
(Other definitions for traction that I've seen before include "Which leaves on the line will affect" , "Use of weights and pulleys to heal a fracture" , "Action of drawing or pulling something" , "Pulling - into cart (anag)" , "Medical stretching" .)