Free when the reel is broken by the rough sea (7)
I believe the answer is:
release
'free' is the definition.
(to release someone is to free them)
'the reel is broken by the rough sea' is the wordplay.
'is broken by' is an anagram indicator (a broken form of the letters).
'the rough' indicates anagramming the letters (a rough or broken ordering of the letters).
'reel' with letters rearranged gives 'rele'.
'sea' is an anagram of 'ase'.
'rele'+'ase'='RELEASE'
'when' acts as a link.
(Other definitions for release that I've seen before include "Free - delivery" , "Liberate" , "Let go" , "put out" , "loose" .)