Half a mile to the back of the queue? Take shelter (3)
I believe the answer is:
lee
'shelter' is the definition.
(as in lee side, the side sheltered from wind)
'half a mile to the back of the queue?' is the wordplay.
'half a' means to take half the letters.
'to the back of' suggests the final letters.
The last letter of 'queue' is 'e'.
'mile' cut in half is 'le'.
'le'+'e'='LEE'
'take' is the link.
(Other definitions for lee that I've seen before include "Robert E. - - , US hero" , "actor" , "Sheltered from the wind in Cork, perhaps" , "Shelter" , "Area sheltered from the wind" .)