Paddled in sea after boat discovered (5)
I believe the answer is:
oared
'paddled' is the definition.
(I've seen this in another clue)
'sea after boat discovered' is the wordplay.
'sea' becomes 'red' (the Red Sea).
'after' means one lot of letters go next to another.
'discovered' says to take the centre (dis-covered - outer letters removed).
The middle letters of 'boat' are 'oa'.
'red' put after 'oa' is 'OARED'.
'in' is the link.
(Other definitions for oared that I've seen before include "Propelled like a rowing boat" , "ready for a row" , "As some boats flew" , "Adore (anag.)" , "(Of a boat) provided with rowing blades" .)