Follows sailor? Sailor may follow this (7)
I believe the answer is:
dogstar
'sailor may follow this' is the definition.
(the dog star might be used in navigation at sea)
'follows sailor?' is the wordplay.
'follows' becomes 'dogs'.
'sailor?' becomes 'tar' (tar is a kind of sailor).
'dogs'+'tar'='DOGSTAR'
(Other definitions for dogstar that I've seen before include "Bright night light" , "animal on TV?" , "This the brightest" .)