Helpful person's reorganised random sailor's property (15)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

BRICK (rather old-fashioned slang for a supportive friend = helpful person: “You’re a brick”) + anagram (reorganised) of RANDOM , then TAR (slang for sailor). Bricks and mortar = slang for buildings, especially as an investment = property.