Head seen in random encounter (4)
I believe the answer is:
dome
'head' is the definition.
(thesaurus)
'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 "Head" , "Crown" , "Rounded roof with circular base" , "description of church roof?" , "Rounded roof; Greenwich tent" .)