Ship rocks, vessel going around river (10)
I believe the answer is:
icebreaker
'ship' is the definition.
(icebreaker is a kind of ship)
'rocks vessel going around river' is the wordplay.
'rocks' becomes 'ice' (I've seen this before).
'vessel' becomes 'beaker' (beaker is a kind of vessel**).
'going around' means one lot of letters goes inside another.
'river' becomes 'r'.
'beaker' enclosing 'r' is 'breaker'.
'ice'+'breaker'='ICEBREAKER'
(Other definitions for icebreaker that I've seen before include "which opens dialogue?" , "Chatty partygoer without reserve" , "useful at beginning of party?" , "Reinforced vessel" , "useful at parties" .)