Follows sailor, and sailor might follow it (3,4)
I believe the answer is:
dog star
'sailor might follow it' is the definition.
'follows sailor' is the wordplay.
'follows' becomes 'dogs'.
'sailor' becomes 'tar' (tar is a kind of sailor).
'dogs'+'tar'='DOG-STAR'
'and' acts as a link.
(Other definitions for dog star that I've seen before include "Night light" , "slightly flashy night-spot?" , "'Another name for the Sirius constellation (3,4)'" , "What may not be seen on cloudy night" , "Part of 8 [CANIS MAJOR]" .)