Fuss about right drill in wreck at sea? (7)
I believe the answer is:
torpedo
'wreck at sea?' is the definition.
(torpedoing a sea vessel might wreck it)
'fuss about right drill' is the wordplay.
'fuss' becomes 'todo' (I've seen this before).
'about' means one lot of letters goes inside another.
'right' becomes 'r' (common abbreviation).
'drill' becomes 'pe' (I've seen this in other clues).
'r'+'pe'='rpe'
'todo' placed around 'rpe' is 'TORPEDO'.
'in' acts as a link.
(Other definitions for torpedo that I've seen before include "Sea-borne missile" , "Naval missile" , "Explosive missile from submarine" , "Missile form a submarine" , "(Of a project) cause to sink without trace" .)