Lois ran to tower (4)
I believe the answer is:
silo
'tower' is the definition.
(silo is a kind of tower)
'lois ran' is the wordplay.
'ran' is an anagram indicator (letters have run around).
'lois' anagrammed gives 'SILO'.
'to' acts as a link.
(Other definitions for silo that I've seen before include "Tower used for storing fodder" , "Launch site" , "Storage unit for animal feed" , "Farm tower" , "Storage pit, tower" .)