Picked up self-satisfied mood (4)
I believe the answer is:
vein
'mood' is the definition.
(I've seen this in another clue)
'picked up self-satisfied' is the wordplay.
'picked up' indicates a 'sounds like' (homophone) clue.
'self-satisfied' becomes 'vain'.
'vain' sounds like 'VEIN'.
(Other definitions for vein that I've seen before include "Vessel carrying blood towards the heart" , "Irregular streak of colour" , "Leaf rib; ore layer in rock" , "Seam of mineral" , "Rock fissure or minerals therein" .)