Head seen in random encounter (4)
I believe the answer is:
Here is my best explanation:
'head' is the definition.
'in random encounter' is the wordplay.
'in' says the answer is hidden in the clue.
'DOME' is hidden within 'random encounter'.
'seen' acts as a link.
(Other definitions for dome that I've seen before include "description of church roof?", "Head", "Rounded roof with circular base", "A stately building", "Rounded roof; Greenwich tent", "millennium feature", "Millennium building", "Hemispherical roof", "Crown" and "Cupola - millennium building".)