Kind of street lined with gold? (4)
I believe the answer is:
sort
'kind' is the definition.
('sort' can be a synonym of 'kind')
'street lined with gold?' is the wordplay.
'street' becomes 'st'.
'lined with' means one lot of letters goes inside another (I've seen this in other clues).
'gold?' becomes 'or' ('or' is the heraldic name for gold).
'st' enclosing 'or' is 'SORT'.
'of' acts as a link.
(Other definitions for sort that I've seen before include "Kind, type or make" , "Work out" , "Type, category" , "choice of characters frequently used in statistics" , "Classify; kind" .)