Ship in channel around spring (8)
I believe the answer is:
dispatch
'ship' is the definition.
(I know this)
'channel around spring' is the wordplay.
'channel' becomes 'ditch' (a small channel or trench in the ground).
'around' means one lot of letters goes inside another.
'spring' becomes 'spa' (spa can mean a mineral spring).
'ditch' placed around 'spa' is 'DISPATCH'.
'in' acts as a link.
(Other definitions for dispatch that I've seen before include "Communication" , "Sort of rider" , "Military report (sent in haste?)" , "Send off (mail)" , "Send (I, not E)" .)