I see diver returning to a shipping hazard (7)
I believe the answer is:
iceberg
'a shipping hazard' is the definition.
(I've seen this before)
'i see diver returning' is the wordplay.
'see' becomes 'c' (the word for the letter, according to Chambers).
'diver' becomes 'grebe' (diving bird).
'returning' is a reversal indicator.
'grebe' written backwards gives 'eberg'.
'i'+'c'+'eberg'='ICEBERG'
'to' acts as a link.
(Other definitions for iceberg that I've seen before include "One with a cold manner" , "Hazard of polar seas" , "Floating mass (of lettuce?)" , "main danger" , "shunned by sailors?" .)