Houses preferred by sailors (7)
I believe the answer is:
prefabs
'houses' is the definition.
(prefabricated houses)
'preferred by sailors' is the wordplay.
'preferred' becomes 'pref' (abbreviation).
'by' is a charade indicator (letters next to each other).
'sailors' becomes 'abs' (AB is short for able seaman).
'pref'+'abs'='PREFABS'
(Other definitions for prefabs that I've seen before include "Ready-made dwellings" , "Ready-made buildings" .)