Digs up iron bar found outside park by building in temporary setting (6)
I believe the answer is:
prefab
'temporary setting' is the definition.
'digs up iron bar found outside' is the wordplay.
'digs' becomes 'p' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'up' is a reversal indicator (in down clue: letters go upwards).
'iron' becomes 'fe' ('Fe' can be a synonym of 'iron').
'found outside' means one lot of letters goes inside another.
'fe' inserted within 'bar' is 'bafer'.
'bafer' written backwards gives 'refab'.
'p'+'refab'='PREFAB'
'park by building in' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for prefab that I've seen before include "Cheap building" , "Structure made in one place and placed elsewhere, in short" , "Sort of dwelling" , "Manufactured in standard sizes and assembled elsewhere, in short" , "Building assembled from manufactured parts, in short" .)