Boasts at home of lookout post (5,4)
I believe the answer is:
crows nest
'lookout post' is the definition.
(I've seen this before)
'boasts at home' is the wordplay.
'boasts' becomes 'crows' (crow is a kind of boast).
'at' is a charade indicator (letters next to each other).
'home' becomes 'nest' (I've seen this before).
'crows'+'nest'='CROWS-NEST'
'of' acts as a link.
(Other definitions for crows nest that I've seen before include "elevated lookout platform" , "high naval post" , "lookout post" .)