Wrecking boats at sea, mostly old (8)

I believe the answer is:

sabotage

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'wrecking' is the definition.
(thesaurus)

'boats at sea mostly old' is the wordplay.
'at sea' is an anagram indicator.
'mostly old' becomes 'age' (I am not sure about this - if you are sure you should believe this answer much more).
'boats' is an anagram of 'sabot'.
'sabot'+'age'='SABOTAGE'

Can you help me to learn more?

(Other definitions for sabotage that I've seen before include "Deliberate wrecking" , "Deliberately destroy" , "enemy action" , "Got a base (anag.)" , "Scupper" .)

I've seen this clue in The Telegraph.

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