Galleon houses everyone (3)
I believe the answer is:
all
'everyone' is the definition.
(I've seen this before)
'galleon houses' is the wordplay.
'houses' says the answer is hidden in the clue (part of the clue houses the answer).
'ALL' is hidden in the letters of 'galleon'.
(Other definitions for all that I've seen before include "and 16 Across and 23 Across: Even so" , "None excluded" , "The whole amount" , "100%" , "Everyone - complete" .)