Destroyer of third world investment was trendy (7)
I believe the answer is:
warship
'destroyer of third world investment' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe there's an association between them I don't understand?
'was trendy' is the wordplay.
'was' becomes 'wars' (I am not sure about this - if you are sure you should believe this answer much more).
'trendy' becomes 'hip' (I've seen this in another clue).
'wars'+'hip'='WARSHIP'
Can you help me to learn more?
(Other definitions for warship that I've seen before include "frigate perhaps" , "It's armed at sea" , "Fighting vessel" , "Naval asset" , "Eg, destroyer, cruiser" .)