Impressive stone Pict houses (4)
I believe the answer is:
epic
'impressive' is the definition.
(I've seen this before)
'stone pict houses' is the wordplay.
'houses' indicates the answer is hidden within the clue (part of the clue houses the answer).
'EPIC' is hidden within 'stone pict'.
(Other definitions for epic that I've seen before include "Colossal" , "Long account" , "Heroic, huge" , "Tale of heroic deeds" , "of impressive proportions?" .)