Swimmer grabbing both sides of paddle survived (5)
I believe the answer is:
coped
'survived' is the definition.
'swimmer grabbing both sides of paddle' is the wordplay.
'swimmer' becomes 'cod' (cod is a kind of aquatic vertebrate).
'grabbing' indicates putting letters inside.
'both sides of' means to remove the middle letters (only the letters on the sides remain).
'paddle' with its centre taken out is 'pe'.
'cod' placed around 'pe' is 'COPED'.
(Other definitions for coped that I've seen before include "wearing vestment" , "as a priest in ceremony?" , "Made the grade" , "Managed, got by" , "Rose to the occasion" .)