Sea song a six-footer's bashful about (6)
I believe the answer is:
shanty
'sea song' is the definition.
(I've seen this before)
'a six-footer's bashful about' is the wordplay.
'a six-footer' becomes 'ant' (ants have six feet).
'bashful' becomes 'shy' (I've seen this before).
'about' indicates putting letters inside.
'ant' put inside 'shy' is 'SHANTY'.
(Other definitions for shanty that I've seen before include "A sailor's sea song, or a rundown hut" , "Slum ghetto" , "Sea song - hovel" , "Sailors' song - shack" , "Small crude shelter and sailor's song" .)