Wrecked boats terribly old (9)
I believe the answer is:
sabotaged
'wrecked' is the definition.
(sabotage can mean to wreck or ruin)
'boats terribly old' is the wordplay.
'terribly' is an anagram indicator.
'old' becomes 'aged' (similar in meaning).
'boats' with letters rearranged gives 'sabot'.
'sabot'+'aged'='SABOTAGED'
(Other definitions for sabotaged that I've seen before include "Aged boats (anag)" , "Damaged" , "Disabled" , "Incapacitated" , "deliberately wrecked" .)