Transport if trail's destroyed? (7)
I believe the answer is:
airlift
'transport' is the definition.
(airlift is a kind of transport)
'if trail's destroyed?' is the wordplay.
'destroyed?' indicates an anagram.
'if'+'trail'='iftrail'
'iftrail' with letters rearranged gives 'AIRLIFT'.
(Other definitions for airlift that I've seen before include "Berlin relief, 1948" , "means of escape" , "Transport in planes" , "Flying transportation" , "delivery" .)