Send half a mile for a taxi (5)
I believe the answer is:
cable
'send' is the definition.
(send a message by cable)
'half a mile for a taxi' is the wordplay.
'half a' suggests halving the letters.
'for' means one lot of letters go next to another (I've seen this in other clues).
'a taxi' becomes 'cab' (synonyms).
'mile' halved is 'le'.
'le' put after 'cab' is 'CABLE'.
(Other definitions for cable that I've seen before include "Naut. length; transmit" , "Telegram; thick rope" , "A message transmitted" , "Rope; message" , "Telegram; wire rope" .)