Trees seen by pressman stuck in traffic? (6)
I believe the answer is:
cedars
'trees' is the definition.
(cedar is a kind of tree)
'pressman stuck in traffic?' is the wordplay.
'pressman' becomes 'ed'.
'stuck in' is an insertion indicator.
'traffic?' becomes 'cars'.
'ed' going within 'cars' is 'CEDARS'.
'seen by' acts as a link.
(Other definitions for cedars that I've seen before include "Strangely sacred trees" , "Trees with perfumed wood" , "Aromatic trees" , "Sacred (anag) -- trees" , "Fragrant trees of the Lebanon" .)